Dictionary for aliens

Toothbrush (-es): an instrument which looks like a head of tightly clustered bristles (mostly synthetic fibers, although animal bristles are sometimes used as well) attached to a handle. Earthlings usually employ this object under the pretext of oral hygiene, but recent studies have confirmed that the act of brushing the teeth is essentially a ritual which may precede any activity that requires them to use both hands. The idea is to moisten the brush, to apply some toothpaste to it and - most importantly - to wedge the brush into the cavity formed by one relaxed cheek and the (gently) clenched teeth at the same side. Once this is done, earthlings can do whatever comes to their mind: sending text messages, putting food into the fridge, writing things down, updating Facebook statuses, going to the toilet, tying shoes, making sandwiches or - although slightly more advanced - answering phone calls.

Theoretical physicists claim that toothbrushes may cause tiny local distortions in the space-time continuum when used properly: local customs on Earth dictate that teeth should be brushed for 3 minutes (an old-fashioned unit of time, roughly equal to the time it takes to boil an egg), but almost all scientists who have actually seen an Earthling brushing his teeth have noticed that it takes less time on the observer's clock. The precise explanation for this phenomenon is not yet fully understood.