One of my favourite adverts was for Club biscuits. It opened showing a huge red button on the floor with banners and signs all round it saying things like 'Danger - Do Not Push' and 'Keep Out'.
Enter Club biscuit; looks at the button and walks round it for a while, then gently touches the button, then a bit harder and finally ends up jumping up and down like a mad thing on it. The inevitable happens; there's a massive explosion with Club biscuit being blown to bits. Strap line: Jacobs Club, incredibly thick chocolate!