Stealing a rocket, Reed Richards, Sue Storm, Johnny Storm, and Ben Grimm made it to the moon despite the cosmic rays. While Reed bought some Space Lemon-Aid, Sue turned invisible. Reed, with the help of a book called Space Laws And Fun Facts, said the cosmic rays had mutated them, giving them super-powers. Ben, tired of Reed's nerd... dung, grabbed a moon tree (?) so he could beat Reed's... derriere. Reed ducked with his stretching powers.
Johnny almost lit on fire, but the fire went out. A book called Science 101, Duh! told Reed that fire needs oxygen, and since there was no oxygen on the moon... and the heroes quickly died.
Ironically, they were not far from the Blue Area of the moon, home to Uatu the Watcher (and enough oxygen to support life).