Hot coffee, or another hot beverage, can be an effective improvised self-defense weapon. When thrown in the eyes of a mugger, it serves as a good distraction, visual obstruction and visual impairment. (It can also be launched from a longer range than empty-hands.)
Delivered with the same basic mechanic as our Pekiti-Tirsia Kali knife jab, it's fast and hard to dodge. Immediately follow-up the initial tactic by maneuvering to cover or exit, or continue to strike and overwhelm the threat. Even if you don't like coffee, and when accessible in your environment or the opportunity exists, having a hot cup o' Joe in hand is a good common and unsuspecting improvised item for self-defense. That is, of course, you don't have your everyday carry weapons for personal defense at the ready.
Speaking of coffee, check out Black Rifle Company. They have good coffee and fun gear with a great mission.