Liar liar, pants on fire

I came home from school one day, walking through to the kitchen where my mom always seems to be when I arrive. She's tackling the dishes, washing them from whatever grime seems to be caked on. I grab a seat at the table, fiddling with my fingers. She takes notice while pausing with a cup in her hand, " how was school dear?"
My eyes went downcast, "mom, is it true that if you lie your pants will catch on fire?" I meekly ask in a whisper.
She resumes her dish washing, "who told you that dear?"
"Amanda"
She hums, "don't worry dear, that's not true." She picks up a plate, rubbing circles with the sponge, "did you ask to see her tongue?"
"Yes" i said
" and what did you see?"
"A cut running across, in the middle." I smiled, " so, she was lying."
My mother nods, "every time you lie, a cut appears on your tongue." She turns around, facing me,"have you been lying dear?"
I stick out my tongue, all clear of any cuts.