Nah --- just resting - What you say when you're so tired you're basically a pile of

What you say when you're so tired you're basically a pile of used napkins and someone tries to be nice to you.

Nah --- just resting. I'm not slacking, I'm just giving my brain a vacation.

Nah --- just resting. I'm not being lazy, I'm just being efficient.

Nah --- just resting. I'm not out of gas, I'm just saving it for later.