Perhaps. With acute intoxication, a person may giggle a lot, as though everything were terrifically amusing, or act uncharacteristically silly. He may have trouble remembering things he just heard (a real problem in school!). He may feel dizzy or have difficulty walking straight. Marijuana can cause blood vessels in the eyes to widen, making the eyes bloodshot. On the other hand, these signs might be absent. People can develop a tolerance for marijuana, especially with chronic use, so that it no longer affects them as strongly as it did before.