sparring-partner
/ˈspɑ:rɪŋ; `spɑrɪŋ/ n
1 person with whom a boxer spars as part of training 练拳的对手.
2 (infml 口) person with whom one enjoys frequent, usu friendly, arguments 经常斗嘴的对手
They've been sparring-partners ever since they were at school together. 他俩从一块儿读书起就没停过斗嘴.