To be David Bowie'd means that a man has either:
1. Worn tights without underpants such that the details of their genitals are nearly completely visible to you while you aren't expecting it or,
2. Pulled their pants up so high that said genital details are visible to you.
History
David Bowie was a rocker, famous mostly in the '80's, who wore tight pants (i.e. tights). His pants were so tight it looked like someone crammed
squirrel brains down the front of them. His
moose knuckles can be seen in almost every photo of him. For an excellent visual example watch the movie "The Labyrinth". If you do ;however, be aware that you will be David Bowie'd.