Final answer:
A customer getting a cut in the gum when eating a fish dinner is most likely a result of an injury from a fish bone.
Step-by-step explanation:
A customer getting a cut in the gum when eating a fish dinner is most likely a result of an injury from a fish bone. Fish bones are sharp and can cause cuts or punctures if they come into contact with the sensitive gum tissue. It is important to be careful when eating fish and to remove any bones before consuming.