My 5 year old asked where babies come from and I panicked
I went with 'your mom's belly' and he goes 'yeah but how did it get there?' I said 'uhhhhh daddy put it there' and he looked so confused. Then he asked 'how does the baby fit?' and I just said 'that's a great question for mommy' and walked away. Pretty sure I failed that one but I'm also pretty sure it's not my turn to explain this stuff.
This made me laugh because my kids ask me stuff like this on my weekend time and I'm always scrambling. The belly answer usually buys you like two weeks before they ask again, so you did alright!