Its meaning has been stretched to include describing a situation where you talk in a public channel (eg. to say "hello") and the other members do not respond.
Oh god I'm so matted.
2) Someone who has done something that is sick in the gross sense
3) Something that is nasty, dirty or filthy
2) Daz: "Gaz got his cock out and put in on my shoulder"
Steve: "Gaz is Matted"
3) I hate picking hair out of drains it's matted