Yes, it’s finally time for THAT old joke! And by extension the insult they shall a-fly. Apparently boob as an insult was born from these very same birds. The origin of the word is probably with Spanish sailors and the word “bobo”, stupid. The boobies apparently used to land on ships where they would be promptly killed and eaten by the sailors. As can be expected, though, there are many cool things about boobies, one of them being the way they hunt. Much like other ocean-bound flying birds, boobies fling themselves into water from on high. What makes this cool is that boobies house air sacs in their faces to cushion the impact into water. When they’re in the water though, they’ll use their wings to swim around to catch as many fish as they can.
Especially blue-footed boobies are pretty odd birds beyond the normal things though, even ruthless by human standards. Unusually for birds, both males and females make reproductive choices based on the looks of their mates. The males present their feet to make themselves attractive to the females and after the eggs are laid, the male will use the brightness of the female’s feet to assess for much care and attention he gives to the eggs and later the chicks. The biggest chick in the brood will also kill its younger siblings either by pecking it/them to death, or by pushing it/them out of the nest if the times are tough and it’s not getting the food it needs. The parents will often simply watch on as this happens or even enable the biggest chick by feeding it more. Killer boobies takes on a whole new meaning, doesn’t it?
PS. If you came here in search of human boobies, you should know that the birds had dibs on the word since the 1500’s whereas the use for a part of woman’s anatomy goes only as far back as the beginning of the 20th century. :-p