resiprocate

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 particular drink 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.