Travis Barker Sucks on Kourtney Kardashian's Toes

Travis Barker is toe-tally whipped -- and he’s not even trying to hide it … dude literally put his money where his mouth is, sucking on Kourtney Kardashian’s toes for her birthday!

Yeah, you read that right -- Travis posted a close-up of Kourtney’s toes fully in his mouth, going all in on what appears to be a foot fetish with zero shame.

Naturally, the internet dropped their thoughts in the comments ... but Travis seemed one step ahead, sneaking the toe-sucking snap in at the end of a massive birthday photo dump for her 47th.

Caption-wise, he kept it sweet and safe ... calling her an "incredible wife" and promising to love her "forever and ever."

But LBR, Hollywood’s getting real comfortable down there lately -- remember, even Selena Gomez gave Benny Blanco’s infamously dirty toes a kiss recently.