Which behavior may indicate that a guest is underage?

The behavior of becoming upset when asked for an ID is often a significant indicator that a guest may be underage. This response may stem from the discomfort or anxiety that someone who is not of legal drinking age feels when confronted with the reality of their age not allowing them to purchase alcohol. Since obtaining an ID is part of the legal process for consuming alcohol, a negative reaction could suggest that they are aware they don’t meet the age requirements and therefore feel defensive when questioned.

In comparison, asking to see the drink menu or ordering a soda is typical behavior for any guest, regardless of age, and does not specifically indicate age-related issues. Waving to the bartender is a benign action that does not provide any information concerning the guest’s age. Thus, the behavior of being upset when requested to show identification stands out as a potential red flag in terms of age verification.