The story
Based on the 1950s slogan “lubbly Jubbly” advertising Jubbly, an orange-flavoured soft drink. The modified version was coined by the English television scriptwriter John Sullivan (1946–2011) as an expression generally used by the character Derek “Del Boy” Trotter, a market trader from London, in the BBC television comedy Only Fools and Horses (first broadcast 1981–1991, with Christmas specials in 1996 and 2001–2003).
Etymology from Wiktionary, CC BY-SA 4.0.