Members of social networks are given opportunities to bestow positive recognition upon one another by means of constructs such as "likes" and "retweets." Although recipients no doubt experience utility from these actions, one might question why these constructs with no intrinsic value for the sender are exchanged at all. Here we formulate a metric for the prestige of a member of a social network based on his or her place within the network and the rate at which "likes" are exchanged within his or her social circle. Simulation reveals that the 1% most strategically-optimized networks exchange likes at an average rate 23.5% higher than that of their random counterparts. This suggests that purely strategic agents, even with no concern for altruism or the general welfare, experience utility from giving social gratification. Further, we show that prestige-maximization creates a selective pressure for structural features associated with social networks including clustering and the small-world property.