slaphappy
1. [ adjective ] cheerfully irresponsible
Synonyms: devil-may-care freewheeling happy-go-lucky harum-scarum carefree
Examples:

"carefree with his money" "freewheeling urban youths" "had a harum-scarum youth"

Related terms: irresponsible
2. [ adjective ] (informal) dazed from or as if from repeated blows
Synonyms: silly punch-drunk
Examples:

"knocked silly by the impact" "slaphappy with exhaustion"

Related terms: colloquialism confused
Similar spelling:   slipup
  slip-up
  slip_up
  slap-up