Final answer:
Chet left hand sanitizer gel dribbled on the dock when he pranked the boys by lighting a cactus on fire.
Step-by-step explanation:
In the given excerpt, Chet left hand sanitizer gel dribbled on the dock when he pranked the boys.
This happened when he emptied the gel on the trunk of a cactus and lit it with a lighter, causing flames to crawl up the trunk and smoke to billow into the night.