The way it works: I wedge myself between their bodies with a bottle in each hand, and stick my face close enough that they can touch it if they want. Which they generally do. If the eye contact from each is good, I sing songs like "Twinkle Twinkle Little Star" or the ABC's. If not so good, I sing a little Sesame Street Peekaboo song that involves them holding their hands over their eyes until I "find" them (which also helps with giving me control over the bottle).
So far, so good. Please no bad internet karma for saying that. :)