3 sentences

1. 小船上的发动机发出噗、噗、噗的声音。

   xiǎo chuán shàng de fā​dòng​jī fā​chū pū, pū, pū de shēng​yīn.

   The small boat's engine made a putt-putt-putt sound.

   Source: Dong Chinese Dictionary

2. 他忍不住噗的一声笑了出来。

   tā rěn bù zhù pū de yī shēng xiào le chu​lai.

   He couldn't help but burst into laughter.

   Source: Dong Chinese Dictionary

3. 那块石头噗的一声掉进了泥沼里。

   nà kuài shí​tou pū de yī shēng diào jìn le ní​zhǎo lǐ.

   The stone fell into the swamp with a plop.

   Source: Dong Chinese Dictionary