My teammate is late and I am going to laugh at him.
Do you know why they are late?
Yes, I actually make them late deliberately
It's really rude to make fun of someone for something that you are causing. Maybe you shouldn't be making people late.
It's not like I expect them to always be on time.
Causing your teammate to be late is rude and it's especially mean to make fun of them for something that you caused. Being late can be stressful and you shouldn't cause them unnecessary hardship. You wouldn't want that done to you.