Received an email from Tigerair:
Free baggage upgrade from 15kg to 20kg is applicable on new flight bookings where 20kg of checked baggage has been selected at the time of booking on all Tigerair Australia flights for travel between 01/05/18 – 30/06/18.
On sale from midday aest Wednesday 11/04/2018 until midday aest Saturday 14/04/2018. Checked baggage is not included in the fare and must be added separately at the time of booking. Offer does not apply to booking updates made via Manage My Booking or WebCheck after the initial purchase. Offer is valid on checked baggage only and excludes all other travel extras such as Cabin+ and seat selection. Extras outside of checked baggage, fees and charges do not attract discount. Not available on all flights or days.
Sounds amazing I’ll make sure to pack a pair of pants