(」・ω・)」うー!(/・ω・)/にゃー!
This particular line was found in Haiyore! Nyaruko-san's Opening Theme, Nyarko-san: Another Crawling Chaos (」・ω・)」うー!(/・ω・)/にゃー!
The meme has since caught interest, and it is required to repeat this 3 times:
(」・ω・)」うー!(/・ω・)/にゃー!
(」・ω・)」うー!(/・ω・)/にゃー!
(」・ω・)」うー!(/・ω・)/にゃー!
and it ends with (」・ω・)」れっつ!(/・ω・)/にゃー!