1 - The act of self-describingly handling yours or someone else's genitals as a manner of masterbation.
2 - Being discreet about a sexual mannerism
3 - Simply put, playing with yourself or someone else.
"Did you see the two girls in the field yesterday?"
"No, but i heard they were pushin' eachother's cow".
"I wish i could've seen them pushing cows. I mite've pushed mah cow too".
"Dude! did you hear some one got caught Pushing thier cow in the bathroom at school."
"Ha! Looks like someone didnt know when it is ok to Push thier cow".