Alcohol is obvi not necessary but more fun! But not binge drinking cuz that’s just stupidity, except during early 20s and at uni.
And I don’t think inappropriateness is necessary either and people have difference sense of humor and not everyone will get sarcasm, esp if very subtle.
The Brits have a dry sense of humour.
I’d say HONESTY, actually LIKING the other person and good conversations are essential for a good friendship.
