"25 or 6 to 4"

OK, hands up who gets this song. It's either a bad acid trip or random word association, but it's a nervous, jittery song, like a panic attack. I have masses of respect for Chicago, seeing how long they've survived in the business and what great songs they've produced, but I just do NOT get this. The skittish drum pattern sets the tone, while the short, sharp blasts of brass drive home the worried, sweaty feel. I have no idea what "25 or 6 to 4" means, but I'll bet it's a drug reference. Please correct me if I'm wrong. And please someone, explain to me how Peter Cetera went from singing this to singing the execrable "Power of Love" 20 years later.