YOU SAID:
I was riding a horse while texting my friend.
INTO JAPANESE
私は私の友人、携帯メールしながら馬に乗っていた。
BACK INTO ENGLISH
I was on a horse while texting my friends.
INTO JAPANESE
私は私の友人携帯メールしながら馬に乗っていた。
BACK INTO ENGLISH
I was on a horse while texting my friends.
Okay, I get it, you like Translation Party.