Bugs Bunny's boner is at the same vertical coordinates as the human pants boner guy. He's even leaking some from within his slacks. Or he just spilled his drink. Since he's drinking precum, either way that's precum on his pants.
This is a wonderful party scene. Such a good time. Just three fellas talking university politics and anal sex. Can you tell I want to be there? I would have so much to add to the conversation. Like I could change the ratio to three nude guys and one clothed one. By getting that gorgeous guy in glasses to give me his clothes.
Nudity is an important part of a social life. It's okay to be nude when others aren't. It's even got an acronym: CMNM (clothed men naked men). Or clothed man naked man if it's just two of you. Have you thought how a man's pants-clad leg or cotton shirt would feel against your bare skin. And how he would smile. Nudity is power.
Though perhaps neither of those two guys were actually naked. It may just be that new "Peeper" Instagram filter. Technology is amazing. So are certain men.