Once I was watching my sister try Sonic Adventure for the first time (got it on Steam from a bundle). I had never played Adventure myself but I knew the Megadrive/Genesis Sonics a bit, more than she did in any case.

She's just messing around, finds a small pool (more like blue transparent rectangle) and jumps in, laughing about the complete lack of physics or any watery effect.

Then "wait, what the fuck is that loud music, why is it playing now?"... And I'm like "Yeah, that's the sound of you drowning." "Oh."