search "minicyn" on Google.com or Dictionary.com and both will ask you if you meant to type "minocyn" which is a shortening of minocycline or tetracycline, both antibiotic drugs. Both of those medications are sometimes given to (attempt to) treat acne. Unless I am greatly mistaken, Grohl was a sufferer of acne, and he might be referring to that. (A cyst is a more painful version of a pimple. Mollusks, a.k.a. snails, are slow. "The cysts and mollusks tend to barter" = the cysts stay around until they get traded away and are gone, but the trades are being performed with the molusks, so the cysts stay for a really long time and are ugly and painful and embarrassing.)
search "minicyn" on Google.com or Dictionary.com and both will ask you if you meant to type "minocyn" which is a shortening of minocycline or tetracycline, both antibiotic drugs. Both of those medications are sometimes given to (attempt to) treat acne. Unless I am greatly mistaken, Grohl was a sufferer of acne, and he might be referring to that. (A cyst is a more painful version of a pimple. Mollusks, a.k.a. snails, are slow. "The cysts and mollusks tend to barter" = the cysts stay around until they get traded away and are gone, but the trades are being performed with the molusks, so the cysts stay for a really long time and are ugly and painful and embarrassing.)