Help! crazy sex chat people wont leave me alone!!!!!

HELP!!!!!!!
ok, so i'm online all the time, and i went to school online, so when a person who i didn't recognize IMed me i expected a window to open with "hey steph i'm so-and-so form whereever" and then i would recognize them.
not this time.
make sure to click on the image to make it big enough to read.
so ok, i can't just hang up on them without making fun of them first, but i HATE this kind of stuff.
and i seriously didn't htink people were dumb enough to do this kind of hting anymore, but not only are they trolling for online people, but they're begging for attention.
after i blocked the username, i deleted the erson off my list.
not to say that i didn't get 2 more IMs from probably the same person with different screen names.
i'm sure i'm going to be getting spam IMs now, so if anyone can tell me how to get away from these people i'd appreciate it. since i have to keep my screen name.

