cool trick to catch a fly

ok so i just did this and it worked so i figure i'd post it. a fly was in my bathroom flying around and hitting the window. i wanted to get it out without killing it or squishing it on the window so i took a clear plastic disposable cup and wham put it over the fly as it was flying against the window. it was in there but now how to get it outside? if i just took it off the window the fly would fly out, so, instead, i turned the cup around slowly so that the fly kept flying into the window but first the wall of the cup was in the way then the bottom of the cup was in the way. when the fly was flying into the bottom of the cup, it's like there was a top on the cup since it didn't know it could fly out the other way. ok so maybe a convoluted description but cool!