'The Bachelor' Nick and Raven get Down and Dirty

2/20/2017 6:20 PM PST

It's time on "The Bachelor" for Nick Viall to head to the hometowns of the final 4 girls -- the first stop was Raven's crib down south ... and it didn't take long to get real sloppy.

The couple raced through a swamp on ATVs and got stuck ... the perfect excuse for Nick to lose his filthy shirt and make out with her.

Sometimes you gotta go muddin' to find true lovin'.