To dot someone is to respond to his or her latest message with serveral dots in a row. He or she then becomes dotted.
The dot method is often used to show your lack of interest or displeasment. Common places for this method is Instant Messaging, IRC and mobile text messages.
Person A: Hey man, I just poked my nose!
Person B: ......
Person A just got dotted.
When you see people fighting and one of the fighters is able to land successive blows to the face. All the welts and scars of the victim on their face means they have been dotted by the oponents fists.
Yo did you see that dudes face today? He got dotted up!