crotch glow 

The act of holding one's cell phone low in your lap as to conceal your actions, all the while illuminating yourself from below.

I was trying to have a conversation with Johanna, but she was playing with her phone and giving me a lot of crotch glow.

crotch glow by grasscarp99 November 15, 2011

Glowing crotch 

When people play on their phones during Spanish class. If other kids want to call eachother out on it, they will say "Is that a glowing crotch?" Many people will find it hilarious and disgusting if you refer to phones this way. Indeed, a spanish teacher once said "Stop staring at your crotch and smiling, while poking it." They hide the phone under the legs near the crotch, so that teachers can't see it, and its glowing, so it gets the name "Glowing crotch"

Juan:Sees Andrew playing on his phone "Is that a GLOWING CROTCH?"
Andrew: "What um of course not"continues playing

Glowing crotch by DEPDIP May 22, 2017