To talk someone into thinking they can do something when they really cannot do it or to make someone feel special when they really are not.
Ex 1: Jamie did a round off double back handspring layout. The team then tried to pump her head up into thinking she could pull a full twisting layout, as well.
Cheer Team: Jamie, try a full!
Shaqueelah: uh-uh, ya'll don't try and pump her head up like that when you know she can't do that!
Ex 2: Jamie is running for homecoming princess for her senior year. Her peers are making it seem like they will vote for her and she will win, but they're really just pumpin' her head up.