How to get your plumber to give you a discount

"Yeah sweetheart, the plumbers here now working under the kitchen sink...yes, I'll keep an eye on him and make sure he does a good job, trust me, I'm on top of this as we speak. ...oh and honey, he's already offered to give us a big discount again, you know...like the deal I worked out with him the last 3 times....LOL...he just love my pretty panties baby."