"Now without making any sudden movements, give them an energon goodie" -Kup
"This is getting expensive!" -Hot Rod
"Don't worry, they'll reciprocate." -Kup
"I thought they were supposed to reciprocate! No more!" -Hot rod
(Taken from the Transformers movie)
To draw up a measure of a beverage through a straw shortly after someone you're with has done so from his own cup or glass.
If you plop two glasses of a particulardrink down on da table in front of both you and a companion, and then start greedily sucking up your portion, don't arbitrarily expect your seat-partner to resiprocate --- either he may not be thirsty, or he may not care for whatever liquid-concoction you've served him.