I'm not gonna say how to do it... But here it is, As far as i know i found this glitch myself
I did report to jagex because i was walking around the agility course and about 10 nubs said "reported" so i reported it as a glitch just incase i would be able to defend myself incase of ban.
I saw this glitch people did it with the hood you get from halloween event years back. and i also saw a glitch where the rune 2h was at penis level sticking out it was so funny tons of people followed the kid.
Gotta love doing deformed human And no, you will not get banned. It's simply a graphical glitch. Just make sure not to do the swimming glitch, even though it's graphical, it gives you an advantage in Defender of Varrock.
Its swiftkit like g0tg0t stated... Its a runescape client not a private server. And nice, there was a similar bug about two months ago people were running around G.E thinking they were hot stuff xD.