It's illegal to drink beer in public in St. Louis (with certain exceptions). Nothing specific to buckets.
Municial Code 14.05.010:
> No person shall drink any nonintoxicating beer or intoxicating liquor in any park, public building, street, sidewalk, alley, highway, parking lot, thoroughfare, or other public place unless consumption of intoxicating liquor or nonintoxicating beer in such place has been expressly authorized in writing by the Excise Commissioner. Provided, that nothing herein contained shall be construed to prohibit the consumption of nonintoxicating beer or intoxicating liquor by working persons during mealtime near their assigned work areas, or by picnic groups in public parks, providing that the person or persons consuming beverages are not noisy, riotous or disorderly in any manner.