Learn German: Hören Sie gefälligst auf, mit der Lektüre zu rascheln, anstatt zu lesen! - Damn well stop rustling with the reading material instead of reading!

Gefälligst is a modal particle used to express a very strong, often annoyed demand. Even though it is related to gefallen (to please) and historically meant 'if you please,' it is now used aggressively. It translates well to 'damn well' or a highly sarcastic 'kindly.'

Does Lektüre mean 'lecture' here?

No, this is a classic false friend! Die Lektüre refers to reading material, like a book, magazine, or pamphlet. If you want to talk about a university lecture, you need to use die Vorlesung or der Vortrag.

Why are there two separate zu clauses in this sentence?

The main verb aufhören (to stop doing something) requires an infinitive clause with zu to explain what action is being stopped. That gives us mit der Lektüre zu rascheln. After that, anstatt (instead of) requires its own separate zu infinitive clause, which gives us anstatt zu lesen.

Could I use the verb stoppen instead of aufhören?

Not naturally. In German, aufhören is used when you want someone to cease an action or behavior, like rustling paper. Stoppen is usually reserved for bringing a moving physical object to a halt, like a car, or pausing a mechanical process.