Here's an oldie:
A travelling salesman breaks down on a long country road. He walks along until he comes across a farmer's house. The farmer lets him call a tow truck, but it's going to have to wait until the following day before the tow truck can get out there and bring him back to town. The farmer says: that's okay, i don't get many visitors round these parts, you're welcome to stay the night. The salesman looks around, not much to see, an old stove, a cot in the corner, no tv, no computer, so he says: if you don't mind me asking, what do you do for fun out here? Well, i don't the chance to do this very often, but i'll show you tonight, after supper. So after a meal of homemade baked beans and broccoli in cheese sauce, the farmer motions over to his cot in the corner. He asks the salesman: y'ever hear of fart hockey? Nope, can't say that i have, answers the salesman. Well you take off your pants and britches and sit on that end of the bed while i do the same on the other, i fart and then you gotta fart and so on... wanna play? Well the salesman thinks to himself that the lonely old farmer was nice enough to take him in, let him call town, and cook him a good supper, the least he could do was indulge him in a game.. besides the beans and broccoli were starting to kick in. So the two strip down bare arse and sit at opposite ends of the bed. The farmer lets one rip, then the salesman fires one out, he's actually laughing out loud with the old man until SPLART! the farmer pushes a little too hard and sharts all over the mattress. Oh man, what do we do now? asks the salesman. First period's over, time to change ends! answers the farmer.