Riddle for a June Tuesday

I quietly sit and wait
until someone moves my plate.
By then, it's much too late
and nothing will escape
the destruction I create
because I am now awake.
Sorry, but you can't close my gate.
My wrath you cannot sedate.
I'm not picky about what I take.
But, this promise I do make,
I always give back a rebate.
It's best if you leave in great haste,
because next it's you that I'll taste!

What am I?