It is normal in the sense of for example seeing your friend accidentally slap themselves in the face with a plank, or have forgot to flush right when they're lu

It is normal in the sense of for example seeing your friend accidentally slap themselves in the face with a plank, or have forgot to flush right when they're lucky enough to take a girl home. It's called schadenfreude. Additionally, it is normal to accept derisive talk (= banter) from good friends. If a friend doesn't get a promotion, you can be very humoristically negative about it in way that would in no way be okay with a stranger. So yes, in those ways it is normal to enjoy watching your friends mess up, and it is normal to feel more at ease with it with friends rather than strangers. However, it is not normal to enjoy seeing your friends fail in life, at all. That goes way beyond schadenfreude and even narcissism, straight into sociopathy.