Speaking of the Canada-auto-join thing, I've always had a certain soft spot for Operation CANUCK:
Step 1: Late on the 4 July 1788, while everyone in the US is too busy being drunk, Upper Canada declares independence - the message being declared to the UK parliament on this date.
Step 2: Parliament immediately surrenders to Upper Canada.
Step 3: The peace treaty is promptly ratified, surrendering the entirety of the British Empire to Upper Canada.
Step 4: "Canada" applies to join the US, and is automatically accepted.
Step 5: The US wakes up on the 5 July to discover that now they control the British Empire... sort of, since Great Britain has about twice as many Representatives - and hence electoral votes - as the entirety of the Thirteen Colonies.