I like it, and it does what you set out to do, but I have a few nits.

1) You should state who is saying what, be it the simple 'he said', 'I said', or 'she said' or something more descriptive. On rereading a few lines, it is obvious who says what, but that sort of thing should be immediately apparent.

2) I'm not sure I'm a fan of the "Slap" appearing on a single line as is. I'm not sure what the technical rules towards... sound effects... are, but when I do see them, they are often *slap* (asterisks on both sides of the word.) Actually, I guess it could work, if it supposed to be the narrator thinking to himself, but like I said, I don't know the precise rules for it.