The title of this comic is “Remove Sandals (0/2)”, which is a reference to the World of Warcraft quest goals mechanism. The expectation here is that the bearded character will have to remove both his sandals upon acceptance of the quest from the burning bush in the cartoon.
The cartoon itself is a reference to Christian mythology when a man named Moses meets a god who delivers a message through a burning bush—and, of course, back to the World of Warcraft mechanics, that’s what the yellow exclamation point is all about. The various gods and goddesses of World of Warcraft also deliver quests using this mechanic (the exclamation point, not the bush.)
Link, via Penny Arcade.
Glad I got this explanation. Not being a WoW player, but interested in Christian mythology, I was totally confused by this one until I came here. Thanks.