A hand gesture created and used to shed light on the fact a certain situation has become "awkward". It doesn't look like a turtle, or an awkward turtle, it's just dumb.
Johnny: So, when she said that I was all like *awkward turtle*
Dave: Dude, that's the dumbest thing I've ever seen, plus, it just makes you look like an ass for making the awkward situation more awkward. It doesn't even look like a turtle.
Johnny: Oh, uh *awkward turtle*
Dave: You're a dumbass