slap·hap·py / ˈslapˌhapē/ (also slap-hap·py) • adj. inf. 1. casual or flippant in a cheerful and often irresponsible way: he possessed slaphappy courage. ∎ (of an action or operation) unmethodical; poorly thought out: slaphappy surveying methods.2. dazed or stupefied from happiness or relief: she's a bit slaphappy after such a narrow escape.