口無遮攔

to blab / to shoot one's mouth off / to commit a gaffe

mouth / classifier for things with mouths (people, domestic animals, cannons, wells etc) / classifier for bites or mouthfuls

not to have / no / none / not / to lack / un- / -less

to cover up (a shortcoming) / to screen off / to hide / to conceal

to block sb's path / to obstruct / to flag down (a taxi)