ボコボコburbling, hollow (sounding), holey, full of holes or dents, lumpy, bumpy, viciously beating, hitting and kicking repeatedly, here and there, (sound of) walking slowly

地表(ちひょう)から温泉(おんせん)がボコボコ湧(わ)き出(で)ています。

Hot springs are burbling up from the ground. {burbling, hollow (sounding), holey, full of holes or dents, lumpy, bumpy, viciously beating, hitting and kicking repeatedly, here and there, (sound of) walking slowly}

猿(さる)がドラム缶(かん)をボコボコと叩(たた)いて遊(あそ)んでいる。

The monkey is playfully and viciously beating the drum can, making a hollow sound. {burbling, hollow (sounding), holey, full of holes or dents, lumpy, bumpy, viciously beating, hitting and kicking repeatedly, here and there, (sound of) walking slowly}

穴(あな)があいてボコボコの道路(どうろ)を車(くるま)で走(はし)るのは危険(きけん)です。

Driving on a road full of holes and bumps is dangerous. {burbling, hollow (sounding), holey, full of holes or dents, lumpy, bumpy, viciously beating, hitting and kicking repeatedly, here and there, (sound of) walking slowly}

どのような状況(じょうきょう)であれ、相手(あいて)の頭(あたま)をボコボコに殴(なぐ)ってはいけません。

No matter what the situation, you must not viciously beat up your opponent's head. {burbling, hollow (sounding), holey, full of holes or dents, lumpy, bumpy, viciously beating, hitting and kicking repeatedly, here and there, (sound of) walking slowly}

雹(ひょう)のせいで車(くるま)のボンネットがボコボコになってしまった…。痛恨(つうこん)の極(きわ)みである。

Due to the hail, my car's hood has become full of dents... This is the height of frustration. {burbling, hollow (sounding), holey, full of holes or dents, lumpy, bumpy, viciously beating, hitting and kicking repeatedly, here and there, (sound of) walking slowly}