Making excuses? How's this?
"I'm going to the Burger King to get a medium drink." (takes 20 mile trip there and back)
"I'm dropping off the Salvation Army clothes." (10 mile drive, plus another 10 or so.. funny since the box is in the center of town, and could have been done during errands)
"I'll go pick up my sister." (heard many times, you wouldn't think so!)
I've got a whole list of them. And if all else fails,
"I'm going out for a drive."
