What's going on in this 日本語 comic?

http://twitpic.com/dlrztu
Can you describe what is happening in this image, because the visuals (or more specifically, a visual) made me intrigued. At the part where it says ライトアップ, what is going on?

His penis is radiating light. The Japanese find the mystery of their reproductive organs hilarious because of their widespread under-use  That's it.