The Blurpleberry Supreme is a piece of candy that Numbuh 5 was saving for Numbuh 1's birthday in Operation: J.E.W.E.L.S.. However, it was stolen by Al Sugarh and taken by Heinrich Von Marzipan, who used it to unlock the tomb of King Twotonsofcandy. In operation Z.E.R.O, Numbuh 101 mentions that he has Numbuh 5's Blurpleberry Supreme, along with Numbuh 1's rainbow monkey underwear and Numbuh 4's report that he used against a weredog.
In the comic Operation: G.R.A.N.D.A.D. it is shown that Numbuh 5 got it from the tomb of the candy pirate, Long John Silverfilling (grandfather of Stickybeard), who'd stolen it from Numbuh 5's grandfather a hundred years ago.