The act of flendering is simply when one person is flirting with another person yet not using any verbal or physical actions. They are simply flirting back and forth using their facial expressions. This is often seen through "kissy faces", "blushing", "Winky-Dinks", and the "Shrugging of shoulders combined with a slight smirk". A combination of all these result in what is known as floundering.
Felipe: I enjoyed your use of floundering last night on snapchat
Javier: *Winks *Smirks
Felipe: *Shruggs shoulders while blowing a kissy face and winking his eyes
Carolyne: Wow they are floundering right in front of me.
Flendering- Flirting by using only facial expressions
Throwing your shoulders back in an effort to hide your man-boobs during sex.
With the large pizza still winding its way through Jim's large intestine he was more than a little aware of his recent weight gain. When he pulled off his t-shirt he stayed upright in the bed, flensing madly while making weird grunting noises.