backslapper

One who makes a show of liking another person with profuse or excessive displays of camaraderie, such as vigorous hand clasping, back-slapping, hearty words of greeting, etc.

Japanese Meaning

背中をたたくなど、過剰な親愛表現（友情を示すための挨拶やお世辞）を行う人 / お世辞を惜しまず、勢いよく賞賛や挨拶をする人

What is this buttons?

Google Translation / DeepL Translation

同窓会で、しつこくお世辞を振りまき背中を叩くように親しげに振る舞う人物が会話に割り込み、古い友人の手を次々と握っては大声でぎこちないお世辞を連発した。

Details

Sense（1）

One who makes a show of liking another person with profuse or excessive displays of camaraderie, such as vigorous hand clasping, back-slapping, hearty words of greeting, etc.