Impact Font

Wikipedia excerpt:

Impact is a realist sans-serif typeface designed by Geoffrey Lee in 1965 and released by the Stephenson Blake foundry. Its ultra-thick strokes, compressed letterspacing, and minimal interior counterform are specifically aimed, as its name suggests, to “impact.” Impact has a high x-height, reaching nearly to three-quarters the capital line. Ascenders are short, and descenders even shorter. The face is intended for headlines and has only limited use in text applications. The face bears comparison with the similarly designed, but narrower, typeface Haettenschweiler, the Letraset face Compacta, and the Linotype face Helvetica Inserat.

Impact is one of the Core fonts for the Web distributed with Microsoft Windows; perhaps because of its ubiquity, it is commonly used in image macros.

Such as this one…

It has been used very very VERY frequently on I Can Has Cheezburger