The chip on my shoulder's a little heavy. I have back problems now.

Garofalo riffs on the idiom “a chip on my shoulder,” which connotes defensiveness, resentment, or a readiness to take offense. By literalizing the metaphor—imagining the “chip” as physically heavy enough to cause back trouble—she turns an emotional posture into a bodily burden. The joke suggests that carrying grievance or perpetual combativeness is exhausting and ultimately self-damaging, while also poking fun at her own public persona as outspoken and prickly. The line works as self-deprecating comedy: she acknowledges the stereotype, exaggerates it into absurdity, and thereby both owns and disarms it.