If I'm on call (OC), I'm responsible for the uptime of the system even after hours. So If I'm planning on going hiking, I will inform the secondary OC, or delay plans to a weekend when I'm not OC. Generally I do tend to avoid getting heavily inebriated (although of course there are times when this is unavoidable).

I'm not judging, but just pointing out that I've certainly experienced a different OC culture in the US.