This question is actually a riddle. The answer to this riddle is, "Buoy meets gull." This answer only works when the question is asked as a riddle because otherwise it seems nonsensical.
This type of riddle is based on the concept of word play. The answer works because "buoy meets girl" sounds very much like "boy meets girl," which is a common American-English phrase. The riddle is amusing because it confounds expectations. The recipient of such a question may expect that the questioner is looking for an actual answer to the proffered question and then be surprised when the answer is so far from what is expected.
