Sure. There are times when you let yourself get petty about it.
It was certainly a thing when I had a corporate job. The guys at the top of companies are super competitive. Standing next to them at a urinal, in a gym shower, etc and dwarfing them is kind of a rush.
Same for dating. Some of my favorite relationships were brief, but based totally on the fact that I had a reputation for having a long cock and a woman wanted the fact that she'd fucked me get back to her ex.
I've currently got a situation that seems to be evolving to a cuckold / bull situation. It's not jealousy but some sort of envy, infatuation.
The best thing is you get the benefit of the other guy's imagination in a lot of cases. If he has a three inch flaccid dick that grows to six and he sees you have a six inch flaccid dick, he starts imagining one that doubles like his and not something that plumps up to "only" eight.