There are several ways to get around in Bujumbura. First of all, you can walk. Secondly, there are swarms of bicycles and motorcycles ready and willing to take you where you need to go. You just pick whichever bike (or driver) appeals to you, agree on a price, and off you go.
There are also mini vans that they cram 17 people into, if that suits your fancy.
This enterprising pair decided to hitch a ride on the back of a big red truck while it was driving down the street.