To be in a very happy/random state, often being extremely spontaneous, and laughing at almost anything. Usually arises from extreme tiredness or light-headedness.
John was laughing for an hour today because someone said 'turtle!' He's being really wiffly.
by Andor Gillian June 21, 2011
Rhymes with "sniffly".
I'm all congested and my nose is sniffly-wiffly.
by Heartichokes May 10, 2008