Verb; To push a person, generally an ugly old
woman, crone, hag, witch, etc., into
something hot, such as a fire, hot coals, or an oven. This phrase is an homage to Grettle the Great, who defeated the infamous witch of the candy cottage by heroically pushing her into a hot oven.
Dude, I totally grettled that bitch!
She pulled a grettle when she saved her
brother by pushing the witch into the oven.
That
insult wasn't a burn, it was an all out grettle.