1. Cheerfully irresponsible
   - carefree, devil-may-care, freewheeling, happy-go-lucky, harum-scarum 
2. Dazed from or as if from repeated blows
   "slaphappy with exhaustion"
   - punch-drunk, silly

See also: confused, irresponsible

• Endecott
• ended
• endemic
• endemic disease
• endemic typhus
• endemical
• slimeball
• slimed
• slimily
• sliminess
• slimline
• slimly
• slimness
• slimsy
• slimy
• sling
• slingback
• slinger
• slinger ring
• slinging
• slingshot
• slink
• slinky
• slip
• slip away