To find the location of the mysterious Pink Egg from Banjo-Kazooie, go back to Spiral Mountain. Just above the tree stumps where the speed shoes are located is a hole. In the hole are metal bars enclosing in a Banjo-Kazooie Game Pak. To destroy the metal bars, you will have to learn about Grenade Eggs. Use them to blow up the bars. Go up to Gruntilda's Lair to find a Flight Pad so you can fly to the hole and break open the Game Pak to find the Pink Egg.