The restroom is frequently locked, but empty, so we have to take a key with us down the hall. We theorize that it is always carefully locked because someone is hiding a meth lab there; hence "I'm gonna go check the meth lab."
That got me thinking about other idiosyncratic phrases generated by co-workers.
I think my other favorite is "pineapple box movies," which refers to pornos.
My old co-worker at Edward Brothers, Sue Ann Levack, coined that term. She used to trade porno tapes with other employees, and they would hide the VHS tapes inside the cardboard boxes in which single pineapples used to be sold. She said it was the perfect size for about four tapes.