Mom: I'm getting you a dog!
Me: OMG REALLY?!
Mom: Yeah, what gender do you want?
Me:...
Me: Bitch, please.
Listen here, dumb dumb. You think you're smart because you can type on a keyboard? News flash, so can my nephew, and he drools more than you. The joke here is that the person wants a female dog, which they refer to as a "bitch." It's funny because it's unexpected and kinda rude. Get it now, or do I need to draw you a picture?