Whomovedmychocolate - I must remember that one LOL
I'm very considerate at a checkout. I always ask the person behind me 'do you want to go first, as I have a lot of items?' and if they say no, I take my time, and have a chat with the cashier also, when packing my bags carefully - who wants squashed food after all!!
That way everyone's happy - and a lot of the time the person behind me (who bizarrely isn't in the express queue.. DUH) will only have a sandwich and a bottle juice, so they will go ahead.
And then I'll take my time and pack my hard-won groceries carefully whilst having a lovely chat with the cashier
If I get one of those super ahem.. 'efficient' cashiers (usually young) who fling the groceries down the chute, I'll tell the young cashier to take it easy, and I'll also (if s/he's flinging my fruit and veg about - to 'get rid of his/her queue') ask him/her - do you eat bruised, broken and mangled food? No? neither do I, so stop throwing my food around please or I'll just have to delay everyone here while I go and get some fresh stuff again.... and we don't want that? Do we?
I tend to do only one shop a week now, but I fill a trolley.
My bug-bear is someone who 'oops, forgets' the marscapone / whatever as their shopping is being checked out, and holds the queue up for ages whilst everyones' frozen stuff gets warmer.. oi vey!