Teaching the ~new~ new guy (yes, the last one quit after only one week) how to do Salmonella assays.

Me while watching him handle a tiny 10 g bottle of secondary reagent: Be careful with that, it costs over a hundred dollars a bottle.
Him: Why is it so expensive?
Me: It contains powdered gold.
Him: Haha, no really, why?
Me: It. contains. powdered. gold.