For those who didn't get both endings, here's how to obtain them. Both endings are unlocked when the mantis starts chasing you:
The first ending is obtained by going into the store. I won't spoil what happens, but let me just say that it's the bad ending.
The second ending is obtained by going into the restrooms. Well, let's just say that's the "silly" ending the game creator was referring to.
And yes, I completed the game with both endings.