Schrödinger’s text

It means if you turn your phone off, the text message is both received and not received until you turn it back on and see.

It's a play on the thought experiment Schrödinger’s cat, devised by Austrian physicist Erwin Schrödinger in 1935, which states that you can’t know if the cat is dead or alive until you open the box. So if you’re anxiously waiting for a text that isn’t likely to come, turn off your phone and tell your friends you’re "doing a Schrödinger’s text for a few hours..." this will lessen your worry and the blow if the other person rejects your offer.
See also : LOL  
NetLingo Classification: Online Jargon