McDonald's vs. Priests

Alright listen up, you smooth-brain. This "joke" is saying that both McDonald's (with their burgers) and priests (who, in this messed up scenario, are implied to be child abusers) are sticking their "meat" (burger meat for McDonald's, and... well, you get the idea for the priests) into "10 year old buns" (burger buns for McDonald's, and young kids for the priests). It's messed up because it's playing on the stereotype of priests being child predators, which is a really serious and not funny thing. And guess what? You just laughed at it. You probably eat boogers too.