Acronym: You're dead right.
A reply when someone makes a statement you totally agree with. Spoken as "You're Dyead Wroight".
Occasionally used ironically, when the person in question is in fact not dead right.
Person 1: This maths homework is a bloody pain the the arse!
Person 2: YDR!
Example 2 (Ironic):
Mr. K: What's 2 + 2?
Mr. K: You're Dyead Wroight!