Naw. I hear it all the time as a bartender. I think self deprecating humor is the outward intent. (Make the lady laugh)

But there’s another motive. Manage expectations: If they do happen to see your junk, they’ll be impressed because they assumed you weren’t lying.

These sound kinda smart TBH. I suppose there could be dumb guys who aren’t too macho to joke about having a small dick, but the dumb macho guys definitely tend to be louder.