if you're unpressurised, fly high. It knocks them all out and you get a peaceful trip. 15-16000 works quite well - but you only really get away with it in countries where the rules are seen more as guidelines.
One of our guys ended up at 19000 trying to shut them up.
Watch out for bags of chips though, they go with a good bang up there - which may require an underpant change on landing if you're not expecting it.