The "canned food" joke usually refers to a knight in armor.

Q: What did the dragon nibble on before
bedtime?

A: A mid-knight snack! (Doesn't work verbally, but still good)

Q: What do you call someone with a dragon on
their head?

A: Squashed!

Q: What do you give a dragon with an upset
stomach?

A: Plenty of room!

Q: What's wrong if you see a talking dragon?

A: You're probably just having a Disney spell

An 18th-century vagabond in England, exhausted and famished, came to a roadside Inn with a sign reading: "George and the Dragon." He knocked. The Innkeeper's wife stuck her head out a window.

"Could ye spare some victuals?" He asked.

The woman glanced at his shabby, dirty clothes. "No!" she shouted.

"Could I have a pint of ale?"

"No!" she shouted.

"Could I at least sleep in your stable?"

"No!" she shouted again.

The vagabond said, "Might I please...?"

"What now?" the woman screeched, not allowing him to finish.

"D'ye suppose," he asked, "that I might have a word with George?"

An elven bard walks into a tavern and asks the crowd, "Who's dragon is that outside?"

An older gentleman, dressed in archmage robes stands up, and replies "Mine. Why?"

The bard somberly approaches the mage. "I regret to inform you that the halfling in our party has killed your dragon"

"What!" erupts the archmage. "Your halfling killed Rithvaeraradace. Slayer of the Elminster, Destroyer of Cormyr, Raider of Waterdeep, Ruler of the Dales, Thorn to the Gods, and Bane of all Toril! How did this happen!?"

The bard sheepishly looks at the archmage and replies "Well...the little guy got stuck in its throat!"