One of the three deviated and searched for nappies online prior to the trip.
Rather than relying on external people to make judgement, you could test the hypothesis yourself: write on paper a phrase. Spend one week without ads and document all ads you see. Spend second week saying word N times per day. Also document all ads you see.
Ask N people to do this and report your findings, then you might provide statistical insight and validate your hypothesis.
Otherwise, who's to say one of those students didn't Google it before the trip?
Does anyone have any ways to improve the design of the above experiment?