[Harold leaning back in his chair: Day 1209 of not using sin, cos or tan.]
I've been clean since 2002.
My dad used it to drill a hole from one floor to another at a precise angle to end in a room that isn't directly under the other one. I use it to program videogame things to throw stuff in a specific direction. Or just to make something oscillate.
I used to hate on it but trig is cool actually