The person that suddenly jumped in with with punches flying is none other than his own buddy - Gao Ke.
Gao Ke had nothing to do at night, and was planning to find Xiao Tianyu to play card games, but overheard Zhang Zian and Xiao Tianyu's conversations. When Xiao Tianyu admitted that he had secretly used their drinking water to wipe down his body and kept it a secret, he could no longer hold in his anger and rushed up to serve up some punches to Xiao Tianyu.
He wasn't just doing it for show, but really putting his energy into those moves, making Xiao Tianyu grunt like a pig on its way to slaughter.
The horrible climate in the desert makes it heart to keep calm, and the high temperature has been grinding on everyone's patience and sanity. There's a bundle of explosives in everyone's heart, waiting for just the right time to explode. Some people have greater self control, while some of them don't, igniting at the slightest spark.
Gao Ke was the latter.