From the back cover of the Bantam Spectra first edition: When Wally first saw the alien spacecraft land in his backyard, he figured it was just another one of his "normal" hallucinations, the result of a rare - and relatively harmless - brain disorder. But then the refrigerator started talking and the TV began sending him special broadcasts. Slowly, Wally became convinced that the message was very real - and very urgent: the Oht have landed and, by the time they leave, the earth will look like Yasgur's farm after Woodstock...
Source · ISFDB CC BY 4.0