Don't.
Always use SQL parameters - it removes any confusion from the system and means that your data is always consistent: which removes worse problems further down the line.
But...if you are alergic to them, then send it as a string in ISO 8601 format: yyyy-MM-dd
http://en.wikipedia.org/wiki/ISO_8601[
^]
It's unambiguous and show convert without problems. Just remember to validate it if it is a user input!
But please, store it in a Date or DateTime column - don't be tempted to use a NVARCHAR or similar, it always ends in tears...