Just got an email saying all flights 20% off if booked on 19th May as Wizz Air's 7th birthday celebration. Hope it saves somebody some money. Terms and conditions copied below:
Happy 7th WIZZ Day!
Amazing one day birthday offer
20% off on all flights!
Book on the 19th of May
The discount applies on the cost of the flight, including taxes and is only valid for new bookings. The discount excludes optional charges (such as baggage fee) and booking fee.