i drew mine on my computer screen using a magic pen. i'll sell you a magic pen if you want. do you want black or red, they're the only magic colours. you can try it with biro but you'll probably just fuck up your screen, you'd be better off getting some ketamine and fucking yourself up
I just cut out that apecat-thing I posted here recently and thumb tacked it to my monitor. Works fine!
(PS: The thumb tack is so you don't have to glue something permanently to your monitor. This way, if you ever sell your computer, you don't have to worry about people impersonating you online later on!!1!)