Another even tagged Mark's new girlfriend Bianca Chatfield, who starred on The Block in 2018, calling her a "lucky lady."
Bianca took it in her stride and urged the commenter: "Don’t encourage him I fear there is many more."
Mark, who was originally paired with single mum Ning Surasiang on the reality TV dating experiment, has been dating Bianca since April 2019 shortly after the finale aired.
The couple met by exchanging messages on Instagram and celebrated their first anniversary privately.
"A lot of people wouldn't know we've been together for a year because we were so conscious of keeping it on the down low," Biance told the Herald Sun this year.
"For us, it was a real relationship and nothing to do with TV. Even though I'm a public person I've always kept my personal life private. But now we're like whatever, it's going well and really cruisy."
Mark's hair-raising photo comes as a particular surprise seeing as he was once a former Cleo Bachelor of the Year finalist.
A throwback snap of the ex-army officer at 26 from a past issue of Cleo magazine appeared on the MAFS Funny Instagram page during his season.
In the profile, Mark poses shirtless in a pair of jeans and reveals that his star sign is Libra and that he used to work as a hotel concierge in Auckland, New Zealand.