Pigeonhole Principle for toddlers

The pigeonhole principle states that if you have N pigeonholes, and N+1 pigeons, at least one of the pigeonholes will have to have two pigeons in it. It's used to prove various stuff in freshman-level discrete math classes, and tends to melt many a poor freshman brain.

Here Nick demonstrates the pigeon hole principle using his train set. Professor Franco Preparata would be so proud of him.

There is only one spot left in the Tidmouth Sheds and I
have both Toby and Thomas that need to be parked! What
do I do??? (note: this is what an average CS freshman looks
like too when asked to prove something using the pigeonhole
principle)

Answer: one of the parking spots has to have two trains.
(P.S. No he didn't figure it out himself, same as most
college freshmen he went and whined to a TA for help).

Here's the video of the process as well. Math is SO FRUSTRATING!