Why making them only available in secret location though? I understand the appeal of having "easter eggs" but personally I prefer when there is a way to discover the animations while playing normally rather than having to try weird setups.
I also like the idea of having a level full of goblins and getting 2/3/4/5p animations depending on number of them alive (=the more you f*ck up the more she gets f*cked...!)
Could you maybe make the 4p/5 part of normal gameplay in hard difficulty, so there's a reward for playing this mode?