Always liked this one but hate the "free antidote inside". Why not free anything at all that refers to brain or skull like "free cranium inside"
Or Free Thinking?
I like it Doctor!
I agree, "free antidote inside" is lame. I guess it refers to an antidote "For the cereal that goes to your head"
Some ideas I thought of are
"Contains complimentary grey matter"
"Topps frontal lobe inside"
"Therapy included"
"For thinking outside of the box."
"No pain, no gain"
OK, now I'm being ridiculous . . .