Funch is a Southern variation on the more common usage of funch - a combination of "fuck" and "lunch." In the Southwest United States, funch is used to refer to something you will fuck then eat.
Funching is the greatest thing ever and I´m sure you´ve done it: you´re in bed and you´re uncorfortable because your pillow is roasting due to your enormous hot noggin, so you flip it over to the cold side and enjoy!
yo, my head is fuckin hott, imma funch this bitch.