What does ガスッ mean?


What does the onomatopoeia that appears in red in the image mean? I'm not
really sure if it says ガヌッ or ガスッ ,since I'm not good at identifying
characters, so I'll leave the image (also to give context) [![enter image
description
here](https://i.stack.imgur.com/hGjlH.jpg)](https://i.stack.imgur.com/hGjlH.jpg)




A typical sound that ガスッ describes is the sound made by a solid and rigid but
not too heavy thing (like a wood block) bumping against another solid and
rigid but not too heavy thing. In this case, I think it describes that one
person is bumping against another person a bit too hard, somewhat
metaphorically and exaggeratedly. If it was a quick tap or a soft hug, ガスッ
wouldn't be adequate.

