According to Wikipedia, button mashing is:

Button mashing is the term given to repeated button presses over a short period. Most of the time, button mashing is seen in athletic and fighting video games. (...) Button mashing was first popularized by Track & Field in 1983 (...) Sometimes, random button mashing is actually more effective than skilled button pushing. This is frustrating to skilled players, who consider button-mashing a mindless action. There are many games that greatly rewarded the player for punching, kicking, or shooting a gun as fast as possible, which must be achieved through button-mashing. In order to reduce wear on controllers and allow players to gain the advantages of button mashing without having to actually mash the buttons, some game controllers feature a turbo button. This easily allows the player to maximize performance in games where a single button must be pressed repeatedly, but gives no advantage in fighting games or when two buttons must be pressed repeatedly one after the other. (...) Modern game designers recognize that many players do not enjoy hours of button mashing to complete games. The designers often incorporate auto-fire features or power-ups that alleviate button mashing requirements in their games. Button mashing is still used in gameplay, but sparingly during climactic points, such as a tight grapple with an enemy or breaking free from a confining attack.

Why do I blog this? button mashing refers to the good ol' day of video games but in terms of interaction design it was quite not that effective (not talking about the impacts of your joystick). However, the total craze it generated was quite funny (especially in those old sports games).