Lincoln is going through a major obsession with bubbles phase, especially because it's one of his first words outside of the "survival vocabulary." Once he learned "bah-booohh," Lincoln points to anything slightly resembling bubbles (such as round ceiling bulbs, plastic balls inside his toy vacuum - and oh yes, boobs), and says his spiffy new word over and over. Right now we think it's ridiculously adorable, so we always acknowledge his observations with something like: "that's right Lincoln! Those look just like bubbles!"
I have a feeling this is going to be really fun in public.