Derived from the term 'lazy wank'. After proceeding to masturbate, one does not wipe one's 'man juice' as is conventional. Instead, the pants and trousers are pulled up and the time between wank and wash is a crusty period. Hence, one is making a conscious decision to lazily avoid the simple task of wiping.
(vb) -ing, -ed
To partake in the act of lazanking.
A damned dirty person.
Person 2: 'He's probably just had a lazank'