The instant reaction to produce a cell phone to check messages or calls, even when we know that we've not received any (or checking for cell reception in the event of not receiving calls or texts). Usually occurs when we see others texting or talking on theirs. Largely generated by insecurity. Not to be confused with the biological phenomenon.
Guy 1 receives a text.
Guy 2 immediately checks his phone
Guy 1 - "Man, put that damn phone away! No-one is calling or texting you - you've got a bad case of cellular reflex."