What is "prank lore" here in italics?

Question

What could happen if someone puts sugar in a gas tank? The standard prank lore goes that pouring sugar in a car's gas tank disables the engine and renders the car inoperable.

Answer 1

From dictionary.com...

prank - a trick of an amusing, playful, or sometimes malicious nature
lore - the body of knowledge, especially of a traditional, anecdotal, or popular nature, on a particular subject

In OP's example, the (relatively unusual/whimsical) combination prank lore is a noun adjunct or attributive noun or noun (pre)modifier usage.

It means the body of popular knowledge about pranks - with a heavy facetious implication that it's not "officially-sanctioned" knowledge, and it might not even be true. I know sticking a potato on the exhaust pipe will stop an engine running - I don't know about putting sugar in the fuel tank, but it strikes me as more "vandalism" than "pranking".

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Having become interested in the facts of the matter (as opposed to the use of language), I found this (admittedly, Off Topic) "myth-debunker" on auto.howstuffworks.com...

The problem with this rumor is that it simply isn't true. As it turns out, sugar doesn't dissolve in gasoline. Pouring sand into the gas tank would have about the same effect as pouring in sugar. The sand or sugar might clog up the filter, and that could disable the car, but it's not a sure thing.

Answer 2

There isn't any special meaning to the words as a pair; it's simply the lore of pranks.

lore n. the body of knowledge, especially of a traditional, anecdotal, or popular nature, on a particular subject

In your example, the subject in question is pranks.

prank n. a trick of an amusing, playful, or sometimes malicious nature.

In other words, it's the body of popular knowledge surrounding pranks and tricks. By characterizing it as lore, the sentence is implying that it may or may not be true; that it's something that "everybody knows". It's meant to emphasize the anecdotal or popular nature of the concept.

One would have to do some digging or scientific research to determine if it was really the case. I don't know about you, but I have no interest in exploring it. I have no desire to potentially ruin my car for the sake of proving it, do you?