Long silence, often used in response to a stupid question.

Noun: a friend who is usually only called upon by a friend when a more primary/prominent friend is unavailable.

Taken from the term “second string” in an athletic competition situation. In football, if the star quarterback gets injured during a play, the second string is called off the bench to replace him/her. A “Second String Friend” is essentially benched until needed, if ever.

Synonyms: Plan B, Second Choice, Secondary Friend, Benched Until Needed

blank stare used in texting or email, typically to portray a feeling of disbelief, frustration, or impatience

A series of 3 periods that, like the word "Hmm" can be used as a space filler during an awkward silence. However, they are also used to create suspense for usually unimportant situations, to answer a stupid question, counter a stupid comment, or simply to piss people off because of overuse.

triple dot of awkwardness

used in texting
a way to say that you're not really sure, or lets just not talk about it

Mainly used in chat rooms or forums, in response to a sentence or phrase which cannot be replied to in any other way because it is incredibly stupid or strange.

Also known as an ellipsis, usually used to represent a word or phrase necessary for a complete syntactical construction but not necessary for understanding.
1) Often used at the end of a written sentence to denote trailing off See Yada Yada Yada
2) Used in response to a (written) incomprehensible statement or a rhetorical question