Dylan Sprouse Jokes He Needs to Tuck in 'FUPA' At Victoria's Secret Fashion Show

Dylan Sprouse is taking the crown for red carpet one-liner of the year ... cracking a hilarious quip while on the red carpet at the Victoria's Secret Fashion Show.

The former Disney star was dressed to the nines in a slick navy-blue suit with a loose collar. Before cameras start flashing, Dylan hikes up his pants -- no belt in sight -- and jokes, "Let me tuck in this FUPA here real quick."

For those unfamiliar ... "FUPA" is as an acronym for Fatty Upper Pubic Area.

The paps weren't buying it ... with one shouting back, "No way!" -- before he struck a pose like a pro.

In his defense ... we all might be feeling a little self-conscious surrounded by the likes of Bella and Gigi Hadid, Emily Ratajkowski, Irina Shayk and plenty more supermodels.

Notably, Dylan was there to support his model wife Barbara Palvin who slayed the runway as usual.