How would I do this?

What i’m trying to do is make a func_door kill a player if the player jumps on it twice in a raw, else if the player jumps on a new entity, he’s not killed. I’ve tried a few different things with ply:GetGroundEntity() but can’t seem to do this for the life of me. Could someone please help me out?

I looked at GetGroundEntity on the wiki and it appears that it should work, the example has it hooked to OnPlayerHitGround. Would you mind posting what you have so far?