The finger boys thing is a psychotic take on the, uh, unique practical joke in Japan and Korea where you poke somebody in the butt. People actually do this to other people and think it's funny.
The caption under the boys reads:
"Doing the 'can cho', (being able to point) and others. When this is done from young time, when the anus becomes strong and is difficult to become the hemorrhoids thing is famous even excessively. "
"Kancho" means "enema", and "can cho" sounds like "being able to point", so there's your clever wordplay. You can fill in the blanks on the hemmorrhoid thing. Not all that hilarious, actually, but there you are.
I am so grateful to finally have that one resolved. Those wacky Japanese!
I have found it helpful to do the stretching exercises my physical therapist recommends. Do some core strengthening exercises, such as the ones highlighted at The Mayo Clinic. By keeping your core strong, your back won't put itself in a position to cause that sciatica pain you are having.