Smile!

I’ve been trying to get Finnie to smile for me!  We went for a walk this morning and I got some of these I-am-extremely-happy-to-be-walking-with-you-right-now photos….

…or these half-lip shots.  I refer to this look as the “Elvis look” and I then I start to sing “I’m All Shook Up.”  Poor dog is probably very confused.
my personal favorite so far!

Is the command “smile” trainable?  I’ve been trying to say the word and move the lips up and reinforce with the treats, but I am wondering if this is a worth-while cause?