All woodwind and brass instruments collect moisture and condensation that constantly needs to be removed during performance to prevent any stray gurgles in the sound. Each instrument has different ways of dealing with this.
Brass players have “water keys” (aka “spit valves”) that drain the instrument, although trumpets and horns have so many twists and turns that various slides need to be removed to find moisture that gathers in a specific place. Horn players often need to physically twist and turn and shake their instruments in order to force the moisture to a point in the instrument where they can empty a specific slide or water key.
Woodwind players can swab their instruments periodically – oboists have long feathers for this purpose. Clarinetists and bassoonists are very efficient about it and simply suck the moisture back in! You’ll also see woodwind players using cigarette paper to get moisture out of specific keys.