Ok, try this one- it's actually pretty native as far as humour goes, but I'll try and tell it anyway.
A man visiting a small village in Ireland sensibly walks down to the local pub for a pint. Outside he is confronted by a nun.
"Stop there!", she cried out, "for the sake of Heaven, do not lower yourself to these depths, do not enter this house of sin and temptation".
The man replies, "What do you mean?"
"Drink is a terrible abomination", says she, "for it corrupts the weak and their good intentions. Forsake this temptation, and find the road to salvation".
"Wait now", say he "how can you stand there and preach to me about drink, for it is a pleasure you have never known. Before you can understand something, you need to try it. Otherwise, how can you know it's a bad thing?"
"Well, I suppose I can't", says she "you do have a point there, i must admit".
"How about this", suggests the man "let me go into that pub there- you don't even have to go inside- I'll order you a small drink, and then when you have tasted it, I will listen to and respect your opinion on the evils of drink".
"Well... if it will help you to find your path to God..." says the nun, "alright. I'll do this one thing for you."
"Ok, what would you like?"
"Oh, I don't quite know. What do people drink, anyway?"
"Listen, don't worry, I'll go in and get you a whiskey."
"Wait though", says she "if people see me drinking from a whiskey glass, they might get the wrong impression. Best ask for it in a tea cup."
"Ok, I'm on my way".
The man walks inside the pub, and up to the bar. He asks the bartender "One pint of Guinness please, and... well this might sound a bit strange, but could I please have a shot of whiskey in a teacup?"
The bartender holds his hand to his head and says "Jaysus, is that old drunk of a nun out there again, for feck's sake!?"