1. Create slides with your points in bullet form. This helps depersonalize your presentation so people don't pay attention to you.
2. To help make it worse, put everything you are going to say onto your slides. That way your audience will have even less reason to listen to you.
3. Extra bonus bad: read out loud from your slides. Minimizing your audience's cognitive load keeps them less engaged.
4. Double-extra bonus bad: turn your back on your audience. Eliminating eye contact reduces the human connection even more.
5. Speak in a monotone at a constant speed. Since you are reciting facts that don't even interest you, your audience need not be interested either.
6. Do not practice. By not practicing, and especially, by not practicing by speaking out loud, you can preserve your hesitations and speech disfluencies for your audience. You will also reinforce your dependence on your text.
7. Stand still. By moving, you will only attract attention.
8. Speak for many minutes more than planned, so that your audience feels trapped and impatient.
9. To help with this, you may want to mention every fact relevant to your topic rather than focusing on the most important ones.
10. To help even more, remember to not practice. I can't emphasize enough how important not practicing is to bad presentations.
11. For technical bonus points, use colorful slide backgrounds so that some of your text is illegible. Even if the text is legible, a few superfluous frames and decorations can go a long way in distracting people.
12. For extra technical bonus points, use sound effects and animation in your presentation. Your audience will appreciate them as much as they do cell phone ring tones.
13. Final technical bonus opportunity: don't pre-load and pre-test your files on the equipment. Starting your presentation with tedious computer manipulation helps reduce interest even before you start speaking.

And a few comments I don't want to force into the conceit of the bad presentation list. Slides are mostly bad. Only use slides if there is something you want everybody to see at the same time, presumably because you are saying something interesting about it. For example, a diagram or chart or something. I think there is an argument in favor of putting something in text for the benefit of audience members who aren't comfortable in the language of the presentation, but if so, it should be on paper handouts so that everyone who needs to read what you are saying can do so at their own pace. Also, paper handouts should be in prose, not in bullet points.

If it were up to me, the minimum acceptable presentation would be performed without notes or bulleted slides. And presenters would be cut off completely at the time limit and judged accordingly. People in class need the conclusion less than the presenter needs to internalize the importance of practice and time management.