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2.
The T.D. unit is a standard measurement for smell intensity. The acronym was chosen to be T.D. as its not commonly known as anything else. The measure has typical values from 1 to 5, 1 being a mild stink and 5 a ghastly stench. On the odd occasion a 6 can be recorded but this is often associated with asphyxiation, leading ultimatley to death.
Bob: Hey man keep away from that guy his rocking like 5 T.D. units!

Jim: Nah man i can handle it.........holy shit he stinks!!!!!!!!!! I can't breathe!!!!!!!!!!!!!!!!!!!!!!!

Bob: Dude it must be a 6 then, better get you to a hospital.
by hesti October 11, 2010
 
1.
The T.D. unit is a new unit to enter the SI system of units. The T.D., otherwise known as the Toan-Dang, is a way of measuring stink/pong levels of someone or something.
A T.D. unit gives you a way of measuring odours. 0 T.D.'s indicates a neutral atmosphere, where as the definition of 1 T.D. is the peak of one's body odour. 2 T.D.'s would be twice as worse and so on. 4 T.D.'s is critically bad where 5 T.D.'s is death.
by grouch johan October 22, 2008