After giving your girl a good rogering in her hiney, You spread her buttcheeks and press her ass against a pain of glass thus creating the apperance of a Red Dot.
To dot someone refers to the red or green dot that you see on them from the laser beam projected as your guns aiming device. Generally means you are going to shoot them.
1.I'll dot a boi for talkin down on my team.
2.If you got a prblem wit me, you better dot me before i dot you.
3. we was dottin suckas all day.
4.Dat boi got dotted.