As a Dutchman, I believe I'm qualified to give you some advice on this. I know english humor well through television, and I visit Germany regularly so...
Try to avoid any humor that is denigrating; so no sarcasm! Germans usually don't like that. Never make a racist commment or a comment about the war or something like that.
Also try to see what kind of jokes they are making, and make sure you laugh at them! even if you don't like them. Try to discuss a funny subject that they brought up and then try making it funnier.
English humor is very liberal; they like to shock. Perhaps the best example is John Cleese in Fawlty Towers: the Germans. Try and get some inspiration for that about the problem. I'm sure it will give you a good laugh! haha
http://www.youtube.com/results?search_t ... q=fawlty+t
Hors' douvres must be obeyed at all times!!! hahaha
greetz
Bucc.
P.S. this post is based on my personal experience. I'm not trying to insult anyone, I'm just trying to help out my fellow PUA here. If there are German friends who would like to help. Please do, my German game can always use some improvement.