Skyler Gisondo's penis, probably

 

First, check the bulge in this candid shot of Skyler Gisondo.  Notice that he's packing, and he dresses right (puts it in the right side of his pants)

Next: playing softball in Wet Hot American Summer: 10 Years Later (2017), Deegs (Skyler Gisondo) pretends that a baseball bat is his penis (he also pretends to masturbate it and suck it).

Look carefully at the bulge he's displaying here. It's on the right.

Now tell me what this is:

From his twitter feed in July 2017: a gif of Deegs dancing when he reaches first base.  Surely that can't be his dick.

It's on the left side, and we know he dresses right. But there's no bulge on the right, and it doesn't look at all like a fabric crease. As we said in California, "You can see the friggin' teeth marks."  

Deegs is supposed to be calling attention to his penis -- he refers to it several times during the scene -- so maybe it's intentional, a club bulge.

See also: Wet Hot American Summer: 10 Years Later