British Stag Do - is this normal?

Not really sure where to start with this but I’m a bit worried about my dad and wanted to get some outside perspective. He’s 61 and went away last weekend to Plovdiv in Bulgaria for a stag do. It wasn’t even for a close mate of his, it was his friend’s son getting married, so he didn’t really know most of the group. There were about 20 of them from what I gather, mostly younger lads, and from the sounds of it a few of them are a bit… rough around the edges and into that whole “lads on tour” chaos. My dad doesn’t really drink much at all. He’s pretty quiet, keeps himself to himself, more of a pub lunch than a pub crawl type. But obviously he got swept up in it a bit. They were doing some kind of dares/forfeit thing while going from bar to bar and he ended up having way too much to drink. This is the part that’s bothering me. Apparently his “forfeit” was to piss into someone’s pint glass. I don’t even know how that escalates to that point but that’s what he told me (and I get the feeling he’s downplaying parts of it). Someone filmed it, it kicked off, and he ended up getting arrested. He spent the night in a cell over there in Bulgaria. What makes it worse is that the rest of them basically just carried on and then flew home the next day, leaving him to sort himself out. He’s back now but he’s just laughing it off, not really talking about it properly, and just seems a bit like he's playing what happened down. I don’t know if I’m overreacting but it just doesn’t sound like him at all. It feels like he got dragged into something stupid with people who take things too far, and now he’s dealing with the fallout. Has anyone else had a parent or someone older get caught up in this kind of thing? Not sure whether to just leave it or try and talk to him more about it.