Earlier quoted context omitted.
“Caturday hepped up on goofballs [after dental work] -> I was high on opiates on Saturday Caturday -> Saturday Hepped -> Novel synonym for “high” likely influenced by the jazz slang word ‘hep’ which means ‘hip’ or ‘cool’ Goofballs -> 5/500 hydrocodone/APAP, aka Vicodin. The gold standard tooth pain prescription drug, an opioid. In this context.
hepped could also just be "hopped" as in "hopped up on X" which is a relatively common phrase for being on some drugs or medication, but using kawaii speak which often softens vowel sounds, turning the open "ah" sound of the 'o' in hopped into a pronunciation of 'eh'. They couldve taken it further and said "hipped up" for no change in meaning. this may not have all been consciously decided, as many chronically online…
Another Simpsons reference.