You smile at noticing the lie.
"Really?" Applejack said, though she seems unamused, "And how is that a lie?"
You keep your grin, but your suddenly dumbstruck at realizing that you don't know why.
"Well....."
You give a goofy smile and scratch the back of your head.
Applejack gives you a sour look, "Care to think again?"
"I told Applejack that I've been hanging with my friends all noon."
"We decided to have a picnic."