You. Are. My. Boss. If I can't be at work for whatever reason, it falls to YOU to do my job that day since nobody else can. I don't need your obnoxious bulls--- comments or refusal to cover for me.
You're f---ing lucky I haven't ever called in sick or quit on the spot like a certain former co-worker did (who used to be my only half-assed backup), so you can drop the attitude.
It'll be interesting to see what happens next month when I take a week off. I think you're in for a seriously rude awakening.