Usually the toddlers in the crates/barrels are 2-3 yrs old, they are not always the same gender either.
The Vials are always different - some results are good some are bad - some make the drinker smarter/dumber/sick, some make their apperance change, some do some other very interesting things. You're basically taking a chance with the vials.
The monkeys, well there are several monkey events, usually the outcome is fair to good with them, but not always.