SAN DIEGO—Carefully examining the bill for any fragment of conclusive evidence, a local dinner party at Mitch’s Seafood restaurant conducted a full-scale investigation Tuesday night to determine if the tip was included in the check. “It feels like it’s already part of the total, right?” said principal investigator Victor Rodriguez, attempting to decipher the cryptic item codes at the bottom of the receipt before passing the document around to several of his fellow detectives for further review, one of whom ran a rough quantitative analysis by adding up the cost of all the items in his head and comparing that to the amount they were charged. “Did anyone see anything about the gratuity policy on the menu? Don’t they always add it when there’s more than six people? Or does it have to be eight?” After successfully closing the case, the team then conducted another thorough probe minutes later to determine why, after everyone had pitched in money to cover the bill, they were still several dollars short.