"...Ayers retreated into irony as he ended the session. "Yeah, yeah," he said after confirming again that he wrote Dreams, "And if you help me prove it, I'll split the royalties with you. Thank you very much.""
Irony | Define Irony at Dictionary.com
the use of words to convey a meaning that is the opposite of its literal meaning: the irony of her reply, “How nice!” when I said I had to work all weekend.