nope, it can happen alot of ways, happens when you try to do something with a player who has logged out. i've found four so far, and yes the duel arena works too.

Rofl never ever seen that, and if you quick chat your friend and he logs out it says
"your friend has stopped playing runescape" lmao
Sounds like hes quit or something

can you reproduce it at will? or did it randomly come up?

Of course he can reproduce it -.- dont ask stupid questions.. Because its obvious he can, hes an exploiter with amazing glitching skills and this isn't a glitch but it is a interesting crack in runescape. There may be other interesting quotes, apparently if you examined a rune helm in classic it would say ab bunch of coding lol

[Hide=1] It happens when you right click a person and they log out then press follow or trade.. and you'll get the message. [/Hide]