Sizing and other questions

[Leevis]

Hey all
New to the forum and need to ask a couple of questions.
I am thinking about buying a BMX but not too sure of what size to get, I am 5'10'' but i have been on a mates bike (he is very small) and his one is a Piranha 300 which has 20" wheels but on looking at the website he got it from it says that it is a 10" frame.
I didnt think that there was such a thing (although it is VERY small and i felt like a giant on it).
He said that i should be looking at something with a frame size of 21TT (whatever that is, 21" i guess) which would make it a good 10" bigger than his which would be a LOT more comfortable.
Anyone have any advice on what size i should be getting, i really dont want to order one only to find its the same size as his
Thanks
Lee

[emon00]

10''!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! midget?

[Leevis]

Yeah he is proper small