Unless you are related to a Chinese person of that name…leave your chin alone. Especially leave it alone if you are a photographer who is doing a self-portrait.
I have seen hundreds of promotional portraits done of photographers – both amateur and professional workers – and every time that the subject has put their hand up to their chin or cheek, it has looked hideous. Also hilarious.
I know this because I succumbed to the temptation with a series of selfies doing just this sort of thing. I must have thought that I would look like an intellectual. As it turned out, I looked like a prat. They were the most stilted and foolish of poses – had I caught anyone else ever looking like that I would have laughed them to scorn and thrown a dead cat at them. Fortunately I had the good sense to bury the images at the crossroads at midnight.
Doing a smile that does not suggest either imbecility or excess gas is hard enough when you have set a self timer going and it is flashing the focus-assist light at you frantically. To add the sort of gesture that looks like the sailor on the Cracker Jack box is just too much folly for words.
If you must play with some portion of your body when the flash goes off, chose a more exotic bit. It might look just as naff, but these days you can make a website and sell images of it.