A twit-twat is someone who insists on using his or her smartphone or any Internet device to look up information on whatever is being discussed, no matter how trivial or casual the subject matter is.
The word can also be used as a verb, such as when someone posts meaningless and trivial information online and insists on telling someone about it.
As a noun
Person 1: Do you remember who the lead singer of Enigma is?
Person 2: Hang on, let me check Wikipedia.
Person 1: You're such a twit-twat.
As a verb
Person 1: Did you guys check out that awesome commercial I just twit-twatted on Facebook?
Person 2: *sigh*