54321 was a chocolate bar of the 80s, discontinued in 1989. Famously remembered from this ad featuring a cover of 5-4-3-2-1 from Manfred Mann, as well as cameos from both Rik Mayall and Ted Rogers at various points over the years.
Appearing in 1992 to advertise 7Up and attempt to appeal to the 'hip' youth demographic is Fido Dido - a character created by Joanna Ferrone and Sue Rose some years previous.