Would I lie to you?

[He puts a finger on each corner of Vriska's mouth and turns them upwards into a smile. As he does so, he gives her a critical, narrow-eyed look, as though judging the result of his actions.]

Hmmmmm... yeeeessss... Yes this is definitely a much better better expression for your face to get stuck in, I think. Beats Little Miss Frownyface anyday!