Answer:
Jeff could act violently because of the power of sugestion of thinking he is under the effects of alcohol. He could expect deshinibition because he thinks he was consumed alcohol.
Explanation:
Some times the power of suggestion can work in strong ways and influence people's actions. This is something that can be seen with the effect of plasebo for example, and also in this case. A person can act out as if it was under alcohol just by being told he is.