This is the first time I've heard this song. I didn't even know it existed. I really like it. It drives you forward from beginning to end. I'm so glad you posted it.
Based on the lyrics it seems he's smitten over a girl who hasn't seemed to have laughed for awhile. Maybe whenever he sees her around she has a down expression on her face. He's trying to convince her that if she gives him a chance at a relationship, he will bring fun and magic and slapstick humor into their relationship and that is the best kind of love relationship she could find...you know...it's what the doctor ordered...laughing is the best medicine kinda thing.
It's not surprising he would call it Slapstick, or single out that type of humor for this song, for it was his favorite kind of humor and it seems he turned to it often when he himself was feeling low.
*goes to listen to the song again*