trickle out(of something)
1. Lit. [for a liquid] to leak or dribble out of something or a place. The oil trickled out of the engine little by little. It trickled out and made a puddle on the floor.
2. Fig. [for someone or something] to go out of something or a place, a few at a time. The dissatisfied members of the audience trickled out of the theater three and four at a time. They trickled out as the evening wore on.