TMW your showing your boss your code and the output, then asks if you can do something else with it. Knowing that it's implemented you try it. Massive amounts of bugs. You think it's a simple fix and make it worse by quickly trying to fix it. Then he leaves. You undo a few changes mess around with the code for a minute and then everything works fine again.

TLDR: Bugs show up when your boss is in the same room as you. Disappear when he's not.