When Igor is trying to teach Duckula about his ancestors:
Duckula: "I don't want to hear about my forebears, my three bears, Goldilocks or anything else in this rottendreary hole!"
When Duckula's computer messes with some numbers at the bank we see an old lady checking her balance. The teller reads (mistakenly) that she is worth ten million Drachmas.
"Ten million! Marry me, you temptress. You vixen of desire."
In "No Yaks Please We're Tibetan", Ruffles' gang of thieves are climbing up a mountain in the Himalayas, planning to steal a huge collection of yakhair carpets and sell them for a fortune in the department stores of Europe and America.
Burt: Er, boss? Ruffles:(to himself, frustrated) I don't believe it... (to Burt) What now!? Burt: Erm... wot's a yak? Ruffles:(standing on a ledge while the other thieves hang on a rope over the edge, oblivious to the huge yak standing right behind him) "Wot's a yak," he says! A yak is a great fat stupid 'airy great cow wot grows in Tibet. Now, 'ave you got any more stupid questions!? Burt: Er... no, boss. Ruffles: Good! (the yak steps on Burt's fingers) Burt: Well, just a little one. Ruffles: Oh, Gordon Bennett... WHAT!? Burt: Well, it's just, er, could you get your boot off my fingers? (Ruffles groans in frustration; the yak steps off Burt's fingers) Burt: Oh, thank you, boss. (he lets go of the ledge; gravity kicks in, and the four thieves plummet down the mountainside, landing with their usual "three thuds, short pause, fourth thud")
The entire Hoomite Yubi sequence from the first episode' "No Sax Please We're Egyptian". Especially Duckula's Sanity Slippage at the end, when Nanny shows up and it looks like the whole thing is starting over again.
The Running Gag in the first episode where the Crow Burglars keep getting hurt, with four distinct thuds being heard each time.
Igor's nauseating Tastes Like Diabetes personality after getting doused with Von Goosewings personality altering chemicals. In that same episode, Duckula being transformed into a traditional vampire in the same manner.
Even funnier is that Goosewing intended for the chemicals to turn Duckula into a non-vampire, but it instead did the opposite.
Igor's hatred of Duckulas harmonica, which he hides at every opportunity