Geoff Goldblum did that in Independance Day!
I hate acronyms. Aviation is full of them. Commitees earn thousands dreaming acronyms that run together to make a new word! 'PLUTO', 'RADAR', 'ASDIC', etc. There are so many now they don't bother anymore. But ET means to me Extra-Terrestrial, so why not let the 98% (at least) of your readers have a clue what your meaning of ET is?