Start off with an oval shape with a bit of a flattish bottom (to stop it falling over)
Add texture to the body by crossing diagonal lines across it
Draw a short curved line slightly above the body following the shape of the top. The neck is very important - otherwise your pineapple will be unable to swallow things.
From the neck draw a slightly curved zig-zag to give it some awesome pinapple spikes
Layer up your spikes by drawing more just behind the first set
...then some more behind those...
...and more behind those
Just keep drawing spikes until either the pinapple looks like it's probably finished or your arm goes numb. We recommend the first of those.