CONQUERING
then in very small print: Mt. Slide
or
MISSION ACCOMPLISHED (okay, that's 2 words but you could do the same thing and put "accomplished" in small print below MISSION)
BOOYAH!
AWESOME! (with "I'm" in little letters in front of it)
NEXT! (with some journaling to the effect of, "Okay, I conquered the slide, bring on the next challenge!)