If someone is DTR, it means that they are excited to do basically anything. This is especially true of situations of craziness, ridiculousness, randomness, and spontaneity.
DTR can be a lifestyle. It can also be a mood.
friend - "Sure, man! I'm DTR!"
me - "Later we can go climb some buildings and point laser pointers at drunk people!"
Nikhil: I don't know, probably Elana cause she seems DTR
Edgar: ....DTR? you mean DTF?
Nikhil: No, DTR. Down to romp. It's much classier
Edgar & Kiki: Ohhhh.
Fraternity brother 2: Thats the last time we come to a tri delt party, wtf bro.
B: I know, I woke up with DTR this morning.