A hectic week can arouse desires to get one's drink on, but don't crack that bottle yet. State open-container laws conform to federal standards, meaning no person in a vehicle may drink or possess unsealed alcoholic beverages. According to Idaho State Code, alcohol may be transported but no person shall break it open or drink. The only location an unsealed container can be located is in a trunk or behind the last upright seat.
In certain states passengers may have or drink alcohol, but in Idaho, that is a no-no. The one exception: in a vehicle used primarily for transporting people for compensation (like a limo). Another exception is RVs, which can have open containers in the living quarters. Violating these laws will result in a misdemeanor for the driver and an infraction for the passenger.
If you're itching to take your hooch outdoors, keep in mind people may have up to 7.5 gallons of beer or wine in non-glass containers in a city park without a permit, but booze isn't allowed on any street, parking lot, restroom, playground, swimming pool, the Greenbelt or within 250 feet of the Boise River.
And remember: Sharing alcohol or tobacco with the geese or other park wildlife is, in fact, prohibited.