The yellow lines of text pulsates on the menu screen. They are randomly chosen from the list and often feature references to popular culture (e.g. websites, quotes, and video games).
↑"Glowing mushroom" by dehodson – Minecraft Forum, January 31, 2010. "Notch put this in. Congrats Peri. ... Source: minecraft.net/indev. See for yourelf. Put a brown shroom in a perfectly dark room. It glows."