From the game Mega Man 2 for the NES.
Select any boss at the stage select screen and hold down the A and B buttons. The stars in the background will change into small birds.
Taken with permission from Flying Omelette.
Ad blocker interference detected!
Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers
Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.