Random Adoptables

[fadillzzz]

Sorry if this has been asked before
but, I'd like to know how to make the adoption page looks like virtuadopt.com where the users don't know what they are adopting untill the eggs are hatched

My adopt.php page fetch a random adoptables from database and everything seems to be working fine since I remove any info about the adoptables from the adopt.php page

but recently one of the users knows how to work around this random adoption thing

he type in URL to directly access the adoption page for an adoptable like
http://www.domain.com/adopt.php?id=X
and then adopt the adoptable he wants!

So does anyone know how to make the adoption page like virtuadopt?