挠痒

wǒ zhǐ hǎo chuān shang cháng xiù yī fu yǐ miǎn zì jǐ náo yǎng

我只好穿上长袖衣服以免自己挠痒。

I had to wear long sleeves to stop myself scratching.

nǐ bāng wǒ náo yǎng wǒ bāng nǐ náo yǎng

你帮我挠痒，我帮你挠痒。

You scratch my back and I'll scratch yours.