Well there are 2 stories:
The cool story is, that is a combination of spanish and german, The spanish soy, meaning "I am"/"become" and the german, weiser, for smart, smart man or being smarter.
A combination if try to be as wise and smart as possible. Both a promise to myself and towards others.
The true story is, I stole it from the rpg shadowrun before I even knew what budweiser was because I thought it sounded funny (Yeah, I played shadowrun before I even knew what beer was
basically). And I stuck with it ever since.
Edit: normally it depends on my mood, and the person I talk to which story I give. But I was in a generous mood. So
no spin today!