Sentence:  Everyone is ambivalent about his profession , if he has practised it long enough , but there were still moments when he loved the stage and all those unseen people out there , who might cheer you or <WSD>boo</WSD> you , but that was largely , though not entirely , up to you . 
Meaning of the word marked with <WSD> tags:  show displeasure, as after a performance or speech