Yes, years ago when I was 14, at sleepaway camp. I remember the scene well because it frankly scared the hell out of me.
I went to a sports camp for a few weeks, and most of the other kids were taller than me, but there was one guy in my bunk who I liked, in part because he was around my height (maybe like 5' 5 back then). I don't even remember his name but he was a really nice guy, a good listener and very sensitive to your concerns. Unusual for guys of that age. You could tell he'd been raised well.
One of the weird things about this kid is that he was unusually ripped. Like when he'd change his shirt in the bunk, he was toned like a gym athlete twice his age, most notably with six pack abs. It was absurd and funny to me.
We shared a big communal bathroom with a few other bunks. Sinks along the front wall, toilet stalls along the left side, private shower stalls with white curtains along the right side.
One night late I went in there to brush my teeth before bed. I thought I was alone until I looked in the mirror above the sink and saw some steam rising above the far corner shower, along with someone's towel hanging from a nearby rack on the back wall. I didn't hear any water running.
As I was brushing my teeth, I watched in the mirror as my friend stepped out of the shower naked and walk some 5 feet to grab his towel. I only saw it for two seconds but I was confused and startled. Hanging between his legs was what looked like a baby's elephants trunk, its flaccid skin loose and wrinkled in a similar way. It hung about halfway to his kneecap and must've been the size of a shampoo bottle - maybe 8 or 9 inches for all I know.
Up until that point id only really seen my own flaccid penis, which was like 3-4 inches and circumcised. So his dick seemed like some kind of startling disfigurement, or seemed it at the time anyway. I've seen the term "macrophallus" in a few places, but I'm not sure. Could've just been an extreme end of the bell curve.