A railing

To get his quarter back.

The baby is inside her stomach

Cat ~ see aye tee

Eggses

All animals, buildings don't jump.

Your days are numbered

Correct, the word 'what' has 4 letters in it, 'yet' has three, 'sometimes' has 9, 'then' has 4, 'rarely' has 6, and 'never' has 5.

The fish bowl got knocked over. The bodies were goldfish.

Your finger.

In number base 4.
22 = 10

4 days
Day 1: 2 -1 = 1
Day 2: 1 +2 -1 = 2
Day 3: 2 + 2 - 1 = 3
Day 4: 3 +2 = 5.