Agree with hndlz, Bandwagon and Subscribe.
They'll stretch as you further break them in. The more hardcore things you do in them (like parkour), the faster they'll break in and stretch out. To stretch out the waistband, some people dip it in water and then bike in them or do some sort of activity in them until they're dry. I'd assume that this method would work for the thighs as well if you're willing to quickly soak them again.