3 sentences

1. 别碰我的腋下，我怕痒。

   bié pèng wǒ de yè​xià, wǒ pà yǎng.

   Don't touch my armpits; I'm ticklish.

   Source: Dong Chinese Dictionary

2. 他腋下挟着一个公文包。

   tā yè​xià xié zhe yī gè gōng​wén​bāo.

   He was carrying a briefcase under his arm.

   Source: Dong Chinese Dictionary

3. 那个小孩特别怕痒，一碰到他的腋下就笑得停不下来。

   nà​gè xiǎo​hái tè​bié pà yǎng, yī pèng​dào tā de yè​xià jiù xiào de tíng bù xià​lai.

   That child is very ticklish; he can't stop laughing as soon as you touch his armpits.

   Source: Dong Chinese Dictionary