Jason

No fancy, complicated syntax highlighting here. The goal of this plugin is to allow your bbPress users to post code snippets in their forum topics and replies without having to learn anything new. Basically, any raw HTML/PHP posted within <code><pre></code> or <code><code></code> tags will automatically be converted and displayed in the forum as you’d expect it would.
And additionally, anything posted within <code><pre></code> tags will be automatically escaped from bbPress applying wpautop. This will allow for your forum users’ code snippets to keep their whitespace as they intend.

bbPress Code Snippets

Automatically display HTML/PHP code posted in bbPress topics and replies.

sharadchhetri

This plugin will simply define the css for HTML Preformatted and Code tags.

SimpleCodeSyntax

This plugin will simply define the css for HTML Preformatted and Code tags. Just download the plugin and activate. Please go through with F.A.Q .

bbPress Code Snippets vs SimpleCodeSyntax