「くっ!!」 as a remark of surprise?

[Haruto Uzumaki]

Precursor: [When I first arrived in Osaka in November, let's just say for various reasons, I was unable to secure a place to stay for some time, so I hung out in various public areas, away from other people, to not get in the way. One of the places I stayed at during the day in order to get wifi was a sort of tunnel connecting a shopping mall to a train station, I believe. I stayed in a large square cutout section in the wall next to the door, hope that can be visualized, which is necessary to understand the situation.]
Most people came through the doors, passing by, and didn't notice me, some did and just looked and kept walking/talking like normal. But then a person walked through the doors (I think with friends) and as soon as he looked at me he said 「くっ！」, of course walking past afterwards.
At first, I thought this was an unfinished word, like maybe he was trying to say 「臭っ」 and stopped when he realized there was a person there (I don't think I smelled that bad especially for someone to notice from a distance though). But then eventually, after a few more people came through, another person (I think who was alone this time) made the same remark upon looking at me, 「くっ！！」. Now at that point, I was deeply pondering what such a remark could mean, but I can only assume that they were surprised at seeing someone sitting in the corner on the floor. Is it possible that this is a remark of surprise? Is it something else? I think about moments like these often, and I still can't guarantee to myself that it was an expression of surprise because I can't find anything on such a small expression, and that day contained the only two times I've heard it. I don't doubt my ability to recognize singular mora pronunciations, but at this point I can't even be sure that I heard them correctly because that's how little info I could find... What do you guys think? Thanks

 

[mdchachi]

I was going to guess they may have said クソ used in the sense of "w t f." But I don't have much expertise in the use of クソ and I'm not positive it's used that way.

 

[Toritoribe]

It seems to me that you misheard it. My wild guess is びっくり（した）.

 

[Haruto Uzumaki]

I was going to guess they may have said クソ used in the sense of "w t f." But I don't have much expertise in the use of クソ and I'm not positive it's used that way.

I won't rule it out

It seems to me that you misheard it. My wild guess is びっくり（した）.

Even if I did mishear it, I find it highly unlikely that I missed multiple mora... But because it's been so long since then, I won't rule that out either...
I've heard people say びっくりした before and even though it's usually said fast (out of shock), I have been able to catch it for quite a while (since almost a year ago). If I misheard the one mora as the wrong phoneme, that's one thing, but I would be shocked if multiple mora went unheard... Even when I tried to talk to a guy that kept ending his sentences in whispers, I could at least tell that he was still saying more mora (I don't even know if that's the right way to word it buttt)

 

[Toritoribe]

びっくり can be uttered as っくり as an interjection.

 

[Haruto Uzumaki]

びっくり can be uttered as っくり as an interjection.

Well if that's the case I guess it's entirely possible that I misheard...This does seem to be the most valid explanation for now. Thanks