Daniel Hutmacher has fun with implicit conversion:
Implicit conversions in SQL Server follow a specific, predictable order, called data type precedence. This means that if you compare or add/concatenate two values, a and b, with different data types, you can predict which one will be implicitly converted to the data type of the other one in order to be able to complete the operation.
I stumbled on an interesting exception to this rule the other day.
Click through for an example of date searching with LIKE.