Nightclubs in GTA Online are businesses included in the game as a part of the After Hours update. Any of the ten clubs can be purchased at the Maze Bank Foreclosures website.
To complete this daily objective, you need GTA$1000. Call Merryweather and select the «Ammo Drop» in the menu. After that, wait until the ammunition crate lands near you, select any of your small arms, and pick up the ammo.
The number of rounds of the selected weapon should not be at the maximum. Otherwise, you won’t be able to pick up the ammo. Also, it’s impossible to pick up rockets or grenades this way.