It's spam, I had fun replying to it, the full message was:

8584967339: "hello Pidgeot you there? Haven't heard from u in a while."

Me: GEOT! O.O

Number: "haha if u want to know who this is u got to addd me on Y!ahoo messenger, my name is txtwoman50

Me: No

Number: "hey my phone is about to die, just talk to me on yahoo ;)"

I ten repeated to sending about 100 texts saying obscenities and then let it be. What a waste of time...