If you get done 3 times by any character that increases your "down" count, you can hold the up key button (jump) to load up the testing room. You will be able spawn every plant that has given you a "down" mark to see their lewd animations. Kobold and Wolf cannot be spawned this way.
If you jump past the trick door that starts up the fall and the adventure, you can find another door that takes you to the test room. You used to be able to find a lot of assets there, but the dev updated it so you only get some curiosities now.
