Probably not put them in the cages, maybe keep them in your pocket and make friendly conversation with people interested in the pigs and then say something like 'You seem really interested in guinea pigs, here take this card; it has links to really useful sites that were made by people who know far more about guinea pigs then you could imagine! They are really great sites to read, nicely organized' or something different. I'm not the best at making up dialogs.
Or
If you want to be creepy and shy just walk up without saying anything drop your card in plain site and walk away.
Curiousity helps all owners.