If at first you don't succeed, cry and cry again!
or
Climb up a tree and act like a nut
or
One minds the train, one trains the mind.
or
Tooth-hurty.
or
Billllyuns and billllyuns. Light bulbs are part of the interstellar "goo" that pervades our universe; they are star stuff.
or
There are footprints in the butter.
or