It's pretty fascinating, it's like they have a playbook, and they run through it in every conversation when their absurd claims are refuted/shown to be wrong. In no particular order:
flood the thread with maybe/maybe not related memes
start multiple threads with different questions/answers to existing threads/comments
claim they have 'crunched the numbers' so they know what they're talking about
make multiple other absurd assertions instead of proving the assertion they just got called out on.
claim you haven't done enough research (if you had, you'd know flat earth to be true)
insult your intelligence
call you a sheep for believing everything the gov't tells you
claim you don't have an open mind (because you don't agree with them)
claim they're 'just investigating with an open mind' (because they're not sheep, they're innovative forward thinkers) (as if that somehow makes retarded claims scientifically accurate)
Tell a story that begins with "I used to belive in a round earth but then I.....". (as if that gives credence to the validity of their conclusions)
This is far from the complete list.