Show up with a cup of coffee. Drink coffee.
Is caffeine addiction a thing? I don't know, is it really that addictive?
I drink at least a pot of coffee a day. I don't feel like I need to drink it, but I do because I love coffee. The slight bitter taste is wonderful.
You might benefit by comparing rates of addiction to other drugs. Nicotine and cigarettes are supposedly the most addictive drug. How does caffeine come in comparatively?
What are the health benefits? Caffeine does good stuff for the brain, as far as I've heard. The same can be said for cigarettes and nicotine. I think both increase brain activity over all, and may prevent some degenerative brain diseases.
Half an hour is a long time to talk, most oral presentations I have done in college were less than 20 minutes.
If you can have a visual element, I would suggest a powerpoint with mostly pictures, and few words. Every slide has a picture, and no slide has more than a sentence on it. That way you're not reading off the slides, and the pictures are cute, funny or thought provoking, which bolsters your presentation.
When you find some neat sources about caffeine and what it does, send them my way.
Wait, why is this posted in sexuality?