Wheneve freddy is at the door, just keep it closed. I tend to keep track of the laughs.
1, 2, 3, 4, close (is what I say to myself) and eventually she'll giggle and go back to 4, and you just have to alternate like that because she'll rotate between the last 2 rooms. The only real rng is 4/20 mode because if foxy attacks 3 times, or if you lose more than 50% by 3am, youre pretty much cooked