This probably is just an ambiguously romantic illustration of implied sex. Stephen Hillenburg's art is sometimes hard to read on top of being astonishingly beautiful, making it all the more interesting to look at!
However with Patrick's attitude and expression, I also like to see this as hir being pinned against a wall by an unknown assailant and he's like:
"You sure you want to go down this road, with the Star of Bikini Bottom?" before whooping his ass.
