IKR is an acronym for "I know, right."
IKR is used as an expression of agreement. As the punctuation is nonexistent in the acronym-version of the phrase, context clues must be used to determine exactly what the intended tone is. IKR often connotes simultaneous shock and agreement.
“Did you see what people are saying on Twitter about Prince William?!”
“IKR! It’s crazy! I’m disappointed but not surprised…”
ikr; shrek is great! can't believe you haven't seen it until now but it's whatever....— Eddie (Edwardmck1/Edwardmck2) (@Edwardmck2) April 26, 2019
Ikr, it's like that sometimes— Vote for BTS!!!! 💙👏🏽 (@ChimchimShamz) April 26, 2019