* Not a teacher
Urban Dictionary is a useful tool (one might say even the best) when it comes to slang terms/expressions. But remember that anyone is invited to add a term to the dictionary, most of the terms being invented by random people. They are used by few people in informal situations/environments. There's a very slight chance that you encounter this term with this specific meaning. A lot of entries are not common, even in youngsters' vocabulary.
I came across lots (really!) of slang by reading different things (funny stuff mainly) on the Internet, but this is something I think it's not very common, I have never seen it used as you are saying. It might be known only by its creator and maybe a few mates of him.
As about the definition, it is pretty unclear and illogical, it doesn't make too much sense. Quote:
Boobed/boobing refers to a woman whose torso is seen by you, but her face is not seen because it is covered by some object like paper, book etc.
So
boobed, as the author mentions, is a noun. But it is also a verb (past tense). And it comes from a verb, but it's a noun (the past tense of a verb is a noun). Quite an intricate and interesting matter.
In conclusion, you will find a lot of weird definitions for a lot of words on that website. Be careful how you use them. They could mean something else to one. The
'best' way to learn the common meaning of the slang terms is to see them in different contexts. A meaning, out of many, will stand out, one way or another.