I require explanation, due to my country of origin not being the United States of America
The rest of the phrase is “get along little doggie”. Basically the worst thing you could say on a Wednesday.
The full quote is “Yippee-Ki-Yay, motherfucker!”, uttered by Bruce Willis in “Die Hard”
The cable tv version of die hard 2 that we taped as kids was “Mr. Falcon”.
Yippee Ki Yay originates from the 19th century in the Western United States. I know it as an expression of excitement or joy. Example: While playing as cowboys, who might say Yippee Ki Yay as you (pretend to) ride off on your horse.
This screengrab is in reference to the line that is said in Die Hard movie(s). The father is claiming to say the last word in the movie catchphrase.