meme is a fad thing. No where similar to mnemonic.
After double-clicking fad: "An intense and widely shared enthusiasm for something, esp. one that is short-lived and without basis in the object's qualities; a craze", I wouldn't call it a fad with this definition. A meme could be the interest in origamy spreading in a school (Dawkin's own example in The God Delusion), the interest in Pokémon, where someone begins to play Pokémon in the class and the meme spreads; more gain interest, buy the game and play it as well, maybe pass the meme on to other classes, until someone ruins everything by telling them it's a childish game, giving them a new meme they feel they have to pass on because of being afraid of being viewed as childish. It could also be our map games, which have "mutated" into many different versions, from Map War to Map War 2, the world map game, your Tripe planet map game and even some map games in space.
Dawkins used the term to refer to any cultural entity that an observer might consider a replicator. He hypothesised that one could view many cultural entities as replicators, and pointed to melodies, fashions and learned skills as examples. Memes generally replicate through exposure to humans, who have evolved as efficient copiers of information and behaviour. Because humans do not always copy memes perfectly, and because they may refine, combine or otherwise modify them with other memes to create new memes, they can change over time. Dawkins likened the process by which memes survive and change through the evolution of culture to the natural selection of genes in biological evolution.[5]
Dawkins defined the meme as a unit of cultural transmission, or a unit of imitation and replication, but later definitions would vary. The meme, as analogous of gene, can be selected as "good" or "bad" and then reinforced or eliminated. The lack of a consistent, rigorous, and precise understanding of what typically makes up one unit of cultural transmission remains a problem in debates about memetics.[12] In contrast, the concept of genetics gained concrete evidence with the discovery of the biological functions of DNA. In the context of the natural or life sciences, memetics suffers in comparison because, unlike the idea of genes, memes do not necessarily have or need a concrete medium in order to transfer.