timing

I don't know about you, but I've recently become aware of a behaviour that that to my attention because of its absence in a friend of mine. It's to do with drinking. When out drinking with someone, or several people, there appears to be a sort of unwritten rule of timing ones drinks so that you finish your pints at approximately the same time. It's a nice feeling of teamwork when a group of four or five people can work together, take turns talking, drinking, going to the toilet etc and still finish their drinks at the same time, without ever overtly discussing trying to do that.

It's analagous, I feel to sex where there is a perceived benefit to both parties 'finishing' at the same time. Or am I reading too much into it?