To capture my babies' best faces (or, not their worst ones anyway), I've gotta wait. I've gotta work for it. I've gotta have my bribes at the ready.
In this case, he was already in a glowing mood (James had just been put to bed...no further explanation necessary), and I told him that if he made a nice smile for my camera, I'd tickle him to smithereens afterwards.
See, everybody wins.