My kids are addicted to Portal 2. Watching it, playing it, even talking about it. Even on a really nice day, outside, at the pool, my 3 year old is STILL telling everyone about "GLaDOS the 'tato" and "Wheatley". I spose it could be worse.
https://www.youtube.com/watch?v=eePHBEWlhJI

Maybe your kids played too much portal? xD