A "rare" anxiety disorder that typically starts in childhood. It's main trait is being mute in public. But this trait can extend to nonverbal communication as well. Basically social anxiety on drugs.
Child: *has selective mutism*
Parents: Our kid is rude for not talking in public so instead of taking them to therapy let's leave them like this and continue to be upset at them because it must be a choice cause children LOVE not having friends! Lol!
When a person is spending some face-time with friends, but is also using a mobile device (i.e. smart phone) to be on social networking sites and/or texting others.
Mary: <staring down at iphone>
Sally: "Are you being antisocial right now?"
Mary: "Pardon me, but I'm actually being 'multisocial' because I'm just texting Mike real quick."