It is like shop lifting but you steal things from a bar instead of a shop. You usually steal things like an ash tray or a cool shot glass. It is usually unnoticed and if noticed you usually don't get punished.
On the phone...
Amber: Hey Dick. How's it goin'?
Dick: I'm cool Am. I barlifted this cool martini glass. You wanna trade with you lucky strike ash tray?
Amber: Barlifting is cool.
When you get bored in your apartment, you walk around doing nothing, you go into your kitchen and check what's in the fridge (though you already know there's almost nothing in it) but you do it a couple of times during the day. You also do it at your friends' place. Staring aimlessly inside the refrigerator
Amber: Hey Dick check this out! Mansur's found a new word called fridgespotting!
Dick: Cool, he-he
Amber: Mansur is cool
Dick: yep Am... he's cool as a fridgerator