The afro is a look that's usually associated with the 1970s, but it's a hairstyle that suits many African Americans, men as well as women. The afro requires you to have rougher hair, and floats around the head like a cloud. There are a variety of styles that could be called spike afros though, and these are a little edgier than the traditional afro look.
An afro is typically thought of as the natural way that rough toned hair grows. It floats about the head in a mass, like a cloud or a halo. However, you can add (and should) add conditioner and strengthener to an afro in order to keep the hair strong. You can also add some gel to just the tips of your afro, creating a spiked look at the edges, but still keeping the feeling of a free floating halo. For shorter afros, spikes can add an edge to your look.
While not technically an afro look, the "land mine" can be put into an afro. If you have a longer afro (a minimum of five inches) you can lengthen the spiked look so that you have longer spikes sticking out all around your head. This look is similar to a floating mine that was left in the water to detonate on impact. Unlike punk rock spikes, there should still be a base of your afro left un-spiked (about two inches) with the rest of the hair pulled into the multidirectional spikes.
Another "Spike" afro is that worn by a character named Spike Spiegel. This is the main character of an anime called Cowboy Bebop, who is a common subject for cosplay. Spiegel has a wavy afro, coloured in green, which is curlier than rough. His afro curls up in front and fans out to either side of his head, but the hair at the neck is closely trimmed. This afro, for those imitating the character, is also worn with a pair of side burns.