The One Big Happy from 3/17, in which Ruthie and Joe perform some silly word play together, with Ruthie taking off on the word rattle on a spelling test for Joe:
(#1) Ruthie jokingly — note the expression on her face – interprets /rætǝl/ as Rat’ll ‘Rat will’ (with Auxiliary Reduction; see the previous posting on this blog, “It’s … it’s … it’s …”, about AuxRed)
Ruthie’s move, with a reference to Rat, provokes a grinning follow-up from Joe, who counters with a reference to Pig and some mildly naughty slang evoking U.S. black talk. They high-five in triumph. A sudden upwelling of urban street culture (and a pop-cutural cartoon allusion) in the midst of a spelling test. Their father patiently presses on.
Whence Rat and Pig? As so often in cartoons, there’s something you have to know about for this to make much sense. Rat and Pig aren’t just silly animals the kids picked out of a hat; like Ruthie and Joe themselves, they’re cartoon characters — from Stephan Pastis’s Pearls Before Swine (a strip with a Page on this blog). Rat and Pig are, however, decidedly louche, and given to outrageous word play A pair of testicular Rat and Pig cartoons, from my 2/6/19 posting “Three Pearls”:
(#2) The nut sack cartoon
(#3) The Go Nads! cartoon
(Not like anything you’ll see in One Big Happy.)
Joe’s boo-TAY. This is about as rude as OBH gets. Ruthie’s Rat’ll is merely general informal, but Joe’s boo-TAY is an exaggerated emphatic variant (in eye dialect spelling) of street slang (originally black) booty, here ‘buttocks’. On the various senses and uses of booty, see my 1/2/16 posting “butt/booty, dial/call”.
high fives / high-fives. From Wikipedia:
The high five [AZ: sometimes spelled high-five] is a hand gesture that occurs when two people simultaneously raise one hand each, about head-high, and push, slide, or slap the flat of their palm against the flat palm of the other person. The gesture is often preceded verbally by a phrase like “Give me five”, “High five”, “Up high”, or “Slap hands”. Its meaning varies with the context of use but can include as a greeting, congratulations, or celebration.
There are many origin stories of the high five [most taking it back to the late 1970s, in American sports contexts, mostly involving black players]
Illustrated in #1.
As for the name, OED3 (Sept. 2014) has first cites for the noun and verb (marked as originally U.S. Sport) in 1980.