Does an aspirin overdose give you an acidosis or an alkalosis? I'm confused.

Yes, it is a bit confusing. Aspiring gives you both:

• A metabolic acidosis - caused by the fact that aspirin is an acid (acetylsalicylic acid) and by its interfering with oxidative metabolism (thereby producing lactate and ketones).
• A respiratory alkalosis - caused by aspirin's ability to directly stimulate the respiratory centre.

However, the combined effects are quite small. People who take an overdose of aspirin are usually most at risk for neurological side-effects, like convulsions and comas.