Strohfeuer

Fashion trends (like this, um ... interesting hat) are often just "Strohfeuer" -- there are only a few classics that manage to stick around. A crush can sometimes develop into true love, but often it's also merely "Strohfeuer" (literally, straw fire). And when stocks jump, investors won't make a move if they think it's "Strohfeuer" -- just a flash in the pan.