Hi Abu Bakr Siddiq,
Ofcourse there is no -ve testing technique as such. Whatever invalid data/input you give and try to break the application becomes a negative/dirty testing. Sometimes people inadvertantly use the word technique/type/method, may be that they are so used to such words in their day-2-day activities. Let us not argue or question or put others down here - instead let us make the discussion more meaningful and constructive so that others [freshers] don't get confused. A tester is a constructive destructor and not just a destructor.
Just my 2 cents :-)