Rhywbeth.
It's pronounced: "Roo-beth" although the R should be made with blowing air and no voice.
If you want to learn some basics of spoken Welsh, there is an easy-to-use free mp3 Welsh course at:
http://www.saysomethinginwelsh.com/home/
"You are Welsh" = Rwyt ti'n Gymreig
'Our Friends' in Welsh is 'Ffrindiau Ni' :)
To say "your house" in Welsh, you would say "eich tŷ".
Cymraeg
No in Welsh is dim.
"y diwedd" is how you say it in Welsh language.
In Welsh, you would say "Rwy'n cytuno" to say "I agree."
Draig Gymreig
You can say "it's nice" in Welsh as "mae'n braf."
Great > [Welsh] mawr
"Egg" in Welsh is "wy".
"She is" would be "mae hi" in Welsh.