This Mossman code also works on sale items, where 3 pack of trunks are priced reduced from $69.95 to $54.95 and with the coupon discount the price would drop to $41.22. That's $13.74 per undie vs. $29.95 (the usual price of Mossman trunks).
Standard shipping will cost you $9.95 on orders below $49, so perhaps you should stack up to maximise your savings.
For example, the trunks in the multipack saving bundles will work out almost the same price per trunk as the ones on sale, i.e. the 7 pack will cost you $13.92 per unit with the coupon code - a total of $97.47 with free delivery.
The code expires on the 17th of April and is valid sitewide.