It's not on at the moment, but a cool ad I saw was a Pepsi ad ages ago.
A diner in the middle of nowhere and there is a Pepsi truck outside and a Coke truck outside. At the counter you see one guy drinking a can of Coke and the other drinking a can of Pepsi. They look at eachother and agree to have a sip of the other guys drink. The Pepsi guy tastes the coke and he thinks it's not bad. The Coke guy then tastes the Pepsi and won't give it back because he likes it too much. It's a pretty simple ad, but I liked it.