The 69-year-old arrived back in Washington, D.C. on Thursday night following a trip to California, and was pictured stepping off her plane at Andrews Air Force Base in Maryland wearing a black jacket, above-the-knee black skirt, black heeled boots, and a bold pair of tights featuring a criss-cross pattern.
Her legwear quickly drew the eyes of multiple online critics - who slammed her tights as 'trashy' and 'embarrassing', while accusing the professor of being 'too old' to wear such a bold look.
'I think Jill B has the holidays confused. She must think it's Halloween. What is she 70? Either way she's much too old for fishnets & stilleto booties,' one person wrote.
'Madonna called and wants her trashy look back, Doc,' another Twitter user added.
A number of people compared her to popstar Madonna, with one writing: 'Good Lord, she looks like Madonna's grandmother.'
One Twitter user joked that Jill looked as though she had been shopping at youth-focused fast fashion retailer Forever 21, writing: 'Hey Jill Biden. It’s not called Forever61 for a reason. Forever21 needs a cut off date!!'
'For an additional $29.99 Jill Biden could have accessorized her Halloween costume with the optional broom,' another added.
Several conservative Twitter users also seized upon the opportunity to heap praise on Jill's predecessor Melania Trump, insisting that the 50-year-old would have looked much better in the patterned tights.
'FLOTUS is too ancient to rock fishnets,' one person wrote. 'Melania definitely has the legs for them not crusty old Jill Biden.'
Another added: 'Jill Biden is just too old to be wearing fishnets. It’s gross. But Melania on the other hand would rock them.'
A third chimed in: 'It’s not JUST the fishnets. It’s the whole mess. A miniskirt? All black? Not too springy. The outfit is ugly for a woman of any age. No one pays attention to #Flotus anyway. The only thing I’ve seen are people still talking about #Melania.'
The criticism sparked outrage among Jill's supporters however, many of whom were quick to fire back and praise the First Lady's 'bold' ensemble - while pointing out that she was wearing 'patterned tights' and not 'fishnets' as some tweets incorrectly stated.
'She is wonderful, you are jealous,' one wrote, while another added: 'There is no such thing as age appropriate.'
'Can't believe all the fuss about Jill Biden's tights. In 2021 ffs,' a third person commented.
Many people took the chance to take aim at Jill's conservative critics, comparing the backlash against the First Lady's ensemble to the outrage over a tan suit worn by Barack Obama in 2014, and sleeveless dresses donned by his wife Michelle.
'Jill Biden wore patterned tights (not fishnets, BTW) & conservatives lose their minds. Ivanka wears them all the time and they consider her a paragon of style. And let's not even get started on what Melania does - or doesn't wear. This is Jill's tan suit moment,' one person said.
'Michelle Obama upset them in a sleeveless sheath dress and Barack Obama upset them in a tan suit,' another wrote. 'So now they upset about Jill Biden and her cute ensemble with her patterned tights and ankle boots. She looked very chic.'
Former President Obama was slammed by critics in August 2014 after he wore a tan suit to a news conference while discussing the crises in Iraq and Ukraine, with some insisting that the summer-centric ensemble was 'inappropriate' for such a serious event.
Meanwhile his wife Michelle faced outrage back in 2009 when she donned a black sleeveless sheath dress for her first official portrait as First Lady, with critics claiming it was too 'informal' for such an official picture.
During her flight back from California - before she revealed her controversial outfit at Andrews Air Force Base - Jill played an entertaining April Fools prank on her staff, Secret Service, and reporters traveling with her by dressing up as a flight attendant and serving ice cream bars on the plane.
As food was being served to the press pool, a flight attendant with short black hair wearing a black pantsuit, black face mask and a name badge reading Jasmine walked through the staff, Secret Service and press cabins passing out Dove ice cream bars.
Jill Biden would appreciate if people stopped retweeting this picture of her trashy outfit pic.twitter.com/Z975OU8ebl— Terrence K. Williams (@w_terrence) April 5, 2021
A few minutes later her senior advisor, Anthony Bernal, and her press secretary, Michael LaRosa, came back to the press cabin laughing.
Jill then reappeared in the press section, without her wig, and announced: 'April Fools!'
Bernal and LaRosa reassured the pool they were just as surprised when 'Jasmine' revealed her true identity to them.
The First Lady was 'visibly pleased with her prank', the reporters noted.
And it is not the first time that the teacher has set out to raise a smile.
'I've always believed you've got to steal the joyful moments when you can,' she wrote in her memoir, explaining her love of practical jokes.
'Life is difficult, and if you sit around waiting for fun to show up, you'll find yourself going without it more often than not.'
In her book 'Where the Light Enters: Building a Family, Discovering Myself', published in May 2019, Jill tells how she once climbed into the overhead compartment on a plane, and jumped out to surprise people.
'The White House is a serious place, with serious people, doing serious work,' Biden wrote.
'If you're not careful, it can grind you down.'
She then tells how she pranked the team on her plane on a flight to California, during Barack Obama's first term.
'I had arrived at Joint Base Andrews early, coming straight from teaching my classes, and was the first one there,' she wrote.
'As I boarded Air Force Two, I looked around and had an idea.
'The overhead bins were small, but I knew if I scrunched up enough, I could cram myself into one.'
She then climbed up on a chair, before stepping onto a table and pulling herself into the bin. Jill said she thought to herself: 'Finally, my ballet barre classes were paying off.'
A naval aide helped give Jill a final boost and pulled the compartment's door down.
'When the first person opened the bin to stow his roller bag, I popped halfway out and screamed, 'Boo!' — though it was hard to get it out through my laughter,' Jill recalled.
'Still, my surprise had the intended effect: this poor soul let out a high-pitched shriek and stumbled backward into his seat, a look of utter shock on his face.'
She also told of pulling a prank on her husband, on Valentine's Day in 2009.
Jill jogged two miles from the Vice President's residence to the White House and, while he was in a meeting, she snuck into his office with the help of his assistant and painted 'big multicolored hearts all over his windows for Valentine's Day.'
She wrote: 'When he walked into the office — accompanied by a senator — later that morning, I wasn't there to see his reaction, but I know he was both delighted and embarrassed.'
© Associated Newspapers Ltd.