Fibbing to a deaf person

I don't often fib to Charlie.  I usually go to great lengths to explain what is happening in the environment around him if it relates to something he can't hear. 

But after having a couple glasses of wine, I'm a little lazy.

We were at Pizza Hut tonight for dinner, Rick, Charlie, and I.  I had two glasses instead of my usual one because I had Rick along as a double D.  (Shhh, don't tell my cardiologist, he'd have a fit!)  On the way home, Rick's neck seemed to be on a swivel, and I finally asked him what was wrong.  He said he kept thinking he heard motorcycle engines, and he was looking for them so he could make sure he didn't hit one.  But he couldn't find them, only hear them.

I didn't hear any motorcycle engines, so I started to tease him about the voices in his head.  He decided to just roll down the windows of the car so he could hear better.

At this point Charlie, who had seen us arguing back and forth (and me not signing, which was very rude of me), gave a questioning sound that even in my wine-induced haze I could accurately interpret as "Why did he roll the windows down?" 

I was feeling way too lethargic to go back and explain the whole scenario in sign language, so I just told him, "Rick farted." 

I really AM a bad mother...