The Last Slumber Party (1988)
Man oh man. I bought this on a whim; the DVD was like $4 at Disc Replay.
And what a treat. I haven't watched the other film on this disc,
Terror at Tenkiller, but
The Last Slumber Party is a sleaze-lover's dream. This is Z-grade slasher stuff at its best. Hilariously inept, but seriously endearing. It's full of hysterical dialogue ("Queerbait!" "You're on the rag!"), bizarro murder scenes, and ridiculous heavy metal music.
Completely fun and entertaining throughout, fans of looooow-budget video trash do yourself a favor and just buy this one. You'll want to watch it more than once.