Update: The time a new guy almost drank hydraulic fluid
We were finishing up on a Cessna in the hangar, and this fresh recruit was grabbing stuff for a break. He saw a clear bottle with blue liquid and thought it was fancy creamer for his coffee, lol. When he popped the cap, the sharp smell hit him and he jumped back, almost dropping it. Everyone stopped what they were doing and just stared for a second before bursting out laughing. His face went from confused to horrified when we explained what hydraulic fluid really is. We still tease him about it, but hey, at least he won't make that mistake again. Honestly, it's the funniest thing I've seen on the job in ages.