Someone who flirts with someone, and is initially successfull, but then flushes it all down the toilet by doing something stupid.
#1. Mike is a flirt flusher: Nancy asked him to help her put on her coat and then he grabbed her crotch and flushed all his hard earned flirt points down the toilet! She was pissed!
#2. Shaner is a flirt flusher: He got Nessa's phone number, and then ridiculed her son (not realizing he was her son).