A swosh sound...https://www.youtube.com/watch?v=nZUrn9Hho3A
Candy must be an euphemism for drugs, specially the ones in "rock form" such as crack or cocaine, but now it´s also short for ecstasy as well (Urban Dictionary).
Don´t know if he refers to an airplane with a load of it, or if he felt the smell of the smoke of it when lighted and, all of sudden, was flying (briefly) under the influence. Don´t know if the "extra weight" was litterally or a way of speaking. But, from the last part of the piece, certainly it was the latter.