Oh come on now, be fair! Cliff's approach is a little more subtle than those!
That said I still find that just walking up to a girl, saying hello and asking if you can buy her a drink is the best way to go. There's no pretense, no "fake" humour, just flat-out honesty. If she likes you back, she'll take the drink, even if she's already got a dozen in front of her, as it's an excuse to talk to you. If she doesn't, then a "witty" line isn't going to change that.
To be fair you've either scored or crashed and burned long before you even open your mouth. Apparenty most women assess you walking towards them. The way you walk shows your confidence or lack thereof, if you're smiling it'll mean (in theory) that you'll be fun and hopefully funNY too, and the way you dress will accentuate your best features and also give a clue as to the lifestyle you lead, the job you do, how much money you make etc. Clothes can also demonstrate confidence too and confidence is the single most attractive trait anyone can have. All this will either impress enough to get you a window of opportunity, or not.
Once you've got the window then being natural is the best approach.