na-adjective, noun
free flow of water; random talk; nonsense
Describes something coming out freely or without restraint. For water, it means gushing or flowing out uncontrollably. For speech, it means talking on and on, often without coherence or substance.
水道の蛇口をひねると、水が出放題だった。
When I turned on the tap, water gushed out freely.
彼の話は出放題で、何が言いたいのかわから
His talk was just random rambling, and I couldn't tell what he wanted to say.
Compound of 出 (de, 'coming out') + 放題 (hōdai, 'as much as one likes'). The combination yields the sense of something emerging without restraint.