"Dw i'n hoffi dy feiro di."

Translation: I like your pen.

[RobinV.]

Well, thanks to Duolingo, I now know what a biro is! I've never heard that before, but I'm going to use it once in a while to confuse my friends. ;)
So does anyone use "biro"? and where are you from?

[SirFurboy]

Yes I use "biro". Biro is widely used in the UK. That is because the British Government acquired the license rights on the Biro patent in the war so they could use them in aircraft. Biro never patented his design in the USA or elsewhere (except Argentina) so the term is primarily a British one. Hopefully this answer also accepts "ball point pen".

[keentospeak]

Interesting chat-up line!