Slang Dazed, silly, or incoherent from or as if from blows to the head; punch-drunk. (adjective)
Slang Happy-go-lucky. (adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "slaphappy" in a sentence
"The Russians and Chinese, on the other hand, have a slaphappy habit of making more weapons than they actually need."
"If Pixar delivered a new Toy Story film every three years, I'd be slaphappy."
"She scampered up to everyone in turn, wagging her tail like mad, going person to person, saying howdy, ignoring no one, bursting with enthusiasm and slaphappy joy."