rib each other

現地時間23日に行なわれるイタリア・セリエＡのダービーを前にミランの本田圭祐選手とインテルの長友佑都選手がツイッターで前哨戦をおこなったようです。

ribは例の肋骨ですが，ここは動詞です。さて，どのような意味なのでしょうか。Ume先輩，お願いします。（Kawada）

Honda and Nagatomo duel online before Milan derby

MILAN (AP) -- Opposing Japan internationals Keisuke Honda and Yuto Nagatomo have been ribbing each other online ahead of the Milan derby on Sunday.

Asked by Honda for some Italian lessons, Nagatomo replied on Inter's Twitter feed, "I'm already helping you and you're learning. I'll make you a deal: If you lose the derby you have to dye your hair purple!"

Honda's reply on AC Milan's Twitter account: "Not a chance!"

Asked how he would celebrate if he scores, Nagatomo replied, "With a bow or with some sumo moves with Fredy Guarin like I did last season."

Asked if he would be used at left back by Inter, where he might have to defend Honda, Nagatomo replied, "I've played there more than on the right but it's all the same to me."

http://mainichi.jp/english/english/newsselect/news/20141122p2g00m0sp097000c.html