Don't bother with his half-baked plan, it was clearly made up on the spot.

half-baked 是由 half（一半）和 baked（烤制的）组成的复合形容词，字面意思是"只烤了一半的"，引申为"不成熟的、考虑不周到的"。 这个表达常用于形容计划、想法等未经充分思考或准备不足的状态。