How long does Vicodin stay in the system?

It's like asking how long it takes you to digest corn. It really depends on the person entirely.

Their physical nature, body type, body size, metabolism, what they eat, how much they eat, what they drink, how much they drink, how often they use the restroom, what their output is while they're in the restroom, how much vic you've taken, how long you've taken them for, etc. etc. etc.