A: What do you think of this pop star whose new song has suddenly gone viral?

B: With only one hit song, it’s obvious that he’s going to be just another flash in the pan.

Note: This idiom refers to something which disappoints by failing to deliver anything of value, despite a showy beginning. Some people believe that this phrase derives from the Californian Gold Rush of the mid 19th century. Prospectors who panned for gold supposedly became excited when they saw something glint in the pan, only to have their hopes dashed when it proved not to be gold but a mere “flash in the pan.”