Di(4)di(less emphasized 4th tone or neutral)
弟弟
you can say "nong" to a little brother or sister
Gelala
you can say "nong" to a little brother or sister
In Farsi, you say "برادر کوچک" (baradar kuchak) to refer to a little brother.
You would say "細佬" (sai3 lou2) in Cantonese to refer to a little brother.
If you are also a boy, you would say "kaikaina" for a younger brother (kaikua'ana for an older brother). If you are a girl, you would say "kaikunane" for a brother.
In Punjabi, you would say "ਤੂੰ ਠੀਕ ਹੈ, ਵੇਲੇ" (tū̃ ṭhīk hai, vēlē) to ask "how are you little brother?"
because when she was a little girl she was so white like a chines person and her parents gave her bangs and the bangs made her look chines that chines people thought they robed her and tried to help her but she keep telling them she was Mexican
"Maligayang kaarawan, aking kababatang kapatid!"
Russian for "Little brother, come here" would be Idi syuda, malenkiy brat. It sounds strange in Russian, but then so it does in English :)
If you want to say brother, as in Big Brother politely you pronounce it as: Dai Gou Gou. If you want to say brother, as in Little Brother politely you pronounce it as: Dia Dia. From Calv860
I play with my little brother is 'je joue avec mon petit frère' in French.