I am starting to get sick of getting caught by clips at work

As a corporate worker, I’ve more or less gotten used to clip injuries. These clips hurt a great deal, especially when they’re half inch deep in your thumb.

During lunch break at work yesterday, I was called out in the middle of my meal to sign off on the delivery of some items the company had ordered off Alibaba, some new office supplies and a presentation board.
After picking up at the waiting area, I returned to my office to meet a colleague waiting for me there. She needed updates on a certain project and wanted to know when it’d be ready for presentation to the department heads.

I leaned backwards to sit on my table instinctively. As I was about to answer her, I felt the sharpest pain I’ve felt in a while. It hurt so much that I shouted. Turns out it was a clip on the table.

I noticed a hint of a smile in my colleague's expression when she told me sorry about the clip that made me slightly pissed off. She apologized and I went back to my meal.

These little clip buggers won’t leave me alone. Also, I do not understand what about the situation made it funny to Agnes. I did not want to come off as being too serious but it did not make sense laughing during a serious situation.