The handicap principle is a hypothesis originally proposed in 1975 by biologist Amotz Zahavi[1][2][3] to explain how evolution may lead to "honest" or reliablesignaling between animals who have an obvious motivation to bluff or deceive each other. The handicap principle suggests that reliable signals must be costly to the signaler, costing the signaler something that could not be afforded by an individual with less of a particular trait. For example, in the case of sexual selection, the theory suggests that animals of greater biological fitness signal this status through handicapping behaviour or morphology that effectively lowers this quality. The central idea is that sexually selected traits function like conspicuous consumption, signalling the ability to afford to squander a resource simply by squandering it. Receivers know that the signal indicates quality because inferior quality signallers cannot afford to produce such wastefully extravagant signals.
The generality of the phenomenon is the matter of some debate and disagreement, and Zahavi's views on the scope and importance of handicaps in biology remain outside the mainstream.[4] Nevertheless, the idea has been very influential,[5][6][7] with most researchers in the field believing that the theory explains some aspects of animal communication.
So, Next time you want to impress a girl then do something which could potentially be really costly to you. Examples are singing, dancing, bungee jumping, muscular physique etc. Doing something which could potentially be costly or doing something which is actually costly like buying a ferrari would make you look attractive. Girls want you to make the first move, so the cost of getting rejected would be born by you. Risky and costly moves represent that you have other qualities which are better than the others even after living on the edge and surviving.