yellow-belly sliders

Question
I have two yellow-bellied sliders living in the same tank. My question is;  why do my turtles "face-up" to each other and flip their front feet rapidly in front of the other ones face?   
They do this once or twice most day. When i asked at the pet shop where I got them from they laughed and said they didn't know why. Can you please shed some light on this mystery please!

Answer
It is not much of a mystery- it is a courtship behavior.

Male sliders have long front claws they use to stroke the females face with- the exact way they stroke it changes based on which species it is. If the female tolerates it and responds appropriately, mating will occur.

Now- young turtles will do it seemingly as a practice, and sometimes turtles that cannot mate- wrong size, wrong sex, wrong species, etc. do it and it can be a sign of dominance or bullying.

If it is a sign of aggression, then it will cause stress to the turtle being bullied. Most often, this happens because the tank is too small for each turtle to have its own space.  You may want to consider a larger habitat for them.

A good site for this species is http://www.redearslider.com