Here i found something about it.

https://www.mashed.com/724564/why-you-should-never-bite-into-someone-elses-hamburger-in-oklahoma/#:~:text=It's%20against%20the%20law%20to%20bite%20another's%20burger&text=According%20to%20Delish%2C%20the%20state,a%20widely%20accepted%20social%20rule.