I'm not sure 

Alternative: "I don't know"

In conversation, when the person speaking to you wants you to feel like you're part of the conversation, but doesn't want to give you an opening. This conveniently allows the speaker to continue to ramble on about something trivial while the other person can only stand there and take it.

I'm not sure what your favorite movie is, but mine is Garden State, and this is why...

I'm not sure by jaykay84 August 29, 2009

honestly i’m not sure 

What girls say in response to a question you ask when they start picking up your interest in them, but they aren’t interested

Mark: “Wow that sounds great, what are you doing this evening?”

Samantha: “Honestly I’m not sure…”

Narrator: “And it was that moment, he entered the friend zone”

honestly i’m not sure by Connor4333 March 26, 2023

I'm not just sure, i'm HIV positive

That cartman says when he is asked if he is sure.
episode 1201

Butters:Are you sure we should be doing this?
Cartman:Butters, i'm not just sure, i'm HIV positive!
Butters: OH well i guess thats true..

I'm not just sure, i'm HIV positive by Samanthaa* April 19, 2008

im not sure actually 

What someone says when they don't want to answer a question because they don't want to reveal the embarrassing truth.

Scott: So Bill, when did you first have sex?
Bill: Im not sure actually. It was a long time ago.

im not sure actually by OilikProfessional December 14, 2009

im not sure whether its bleeding any more 

the phrase used to express the feeling of insecurity of ones ear

'u know my ear? im not sure whether its bleedong any more.'

im not sure whether its bleeding any more by batman March 19, 2005

im not really sure how to go about it 

no definition just advice.

What does your heart tell you

‘i like her but im not really sure how to go about it’
‘Just follow your heart bro’

im not really sure how to go about it by Margret_Holmes73 January 11, 2022