Yeah, I've seen his sidekick pictures before. His penis looks a lot like mine, except maybe mines a bit bigger. There was a mixed reaction on gossip sites, "OMG PETE WENTZ HAS A BIG DICK!" and "LOL PETE WENTZ HAS A SMALL DICK!". A mix of both...when infact, his dick is just average. Not big, not small...average. Judging from those pictures at least.
One trick I actually did that proved this was by taking the pic where it's in his hand and flipping it upside down on MS Paint so it's from like his point of view. Judging from that angle, which you can compare to your own mental comparison on what your penis looks like when YOU look at it, you'll see that he's just average. His is a bit smaller than mine but not too much is different. He's in the average range and that's that.