What's the difference between babies and onions?
You don't cry cutting up babies.
Listen up, buttercup. This dude is making a sick joke. Most people cry when they chop up an onion. But this comedian is saying that no one should cry while cutting up babies. Which is a pretty messed up thing to say, just like you are messed up in the head. It is sarcasm at its finest. You are so dumb.