Sende neymiþsýn be abi

 And what do you appear to be brother ?

 I cant understand.....  appear.....

thats the -miþ part

How am Ý going to explain ?

-(y)miþ is being used for a situation that someone has heard. It can be translated as: people say/its appears that/appearently/as Ý have been told.

Its difficult for me to explain in english, i wll just give some examples:

Bu kadýn çok zenginmiþ

This women appears to be very rich

O neymiþ ?

What do they say thats is ?

Adam kalp krizi geçirmiþ

As I have been told that man has had a heartattack.

Kaslarým aðrýyor biraz fazla spor yapmýþsým

My muscles are hurting appearently i have made to much sports.

Hasta olmuþsun

You appear to became ill (is this correct english ?)

I dont know Deli it might be possible, since english isnt my motherlanguage i cant be sure

but in those three sentences you could also use the word appears

Apart from" for a situation that someone has heard"

The meaning in "Sende neymiþsýn be abi"

is a bit different..

sen neymissin means ´you are something I did not know before´ or ´you became something I did not know before´

It is used in situations like :

I say :

-I am the most handsome guy here

you reply

-sen neymissin be abi  (you are telling me I am big headed person here)

or I say 

-I was so jealous so that I hit the guy who was with my girlfriend

you say

-sen neymissin be abi (you did not know my jealousy and you could not think i could hit the guy)

abi means elder brother

==

anyway.. This is used for big headed  people in most of the cases..

Listen to this song for example..

Mazhar Fuat Özkan (MFÖ - Peki Peki Anladýk 

http://www.youtube.com/watch?v=05v6rSJRIQU

Peki peki anladýk (yes yes we got it)
Her þeyden sen anlarsýn (you comprehend everything )
Peki peki anladýk (yes yes we got it)
Her þeyi sen bilirsin (you know everything)
En güzel grubu sen kurdun (you formed the best group)
En güzel ritmi sen buldun (you found the best rhythm  )
En iyi dalgýç sensin
En güzel filmi sen çektin
Peki peki anladýk
Peki peki anladýk
En güzel sen bakarsýn
Peki peki anladýk
En güzel sen aðlarsýn
Ýlk önce sen baþlattýn
En önce sen yavaþlattýn
En uzaða sen gittin
En çabuk da sen döndün
Peki peki anladýk
Sen neymiþsin be abi!
Peki peki anladýk
En güzel sen gülersin
Peki peki anladýk
En güzel sen söversin
En güzel yemeði sen yaptýn
En güzel kýzý sen kaptýn
En güzel tumbayý sen çaldýn
En güzel þarkýyý sen yazdýn
Peki peki anladýk
Sen neymiþsin be abi!
Peki peki anladýk
Her þeyden sen anlarsýn
Peki peki anladýk
Her þeyi sen bilirsin
En güzel grubu sen kurdun
En güzel ritmi sen buldun
En iyi dalgýç sensin
En güzel filmi sen çektin
Peki peki anladýk
Sen neymiþsin be abi!

Guess i have to admit you are right abi, thanks for the correction