This phrase is a way to make fun of people who say 'that's so gay' by changing it to 'that's so straight'. Many gay people (or people who think its offensive) use it instead of 'That's so gay' to show that its a hurtful phrase.
Amy: I got a ton of bio homework to do tonight, we can't go on our date...
Dane: Damn, that's so gay!
Amy: That isn't gay. That's so straight! (like you lol)
Dane: *crys in corner*
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).
Precedes or follows either a gratuitously disrespectful or honest remark, originated in New York City. Used in similar fashion to "no offense" or "to be honest," interchangeably.
Ya mans is wild buns, respectfully. Respectfully he's washed.
After school, The Modells on Jamaica Ave was active. Respectfully.