Breakdown of Прятаться негде, поэтому я не думаю, чтобы он это выдумывал.
это
this / it is
не
not
он
he / it (for a masculine noun) / it (for a neuter noun)
я
I
Questions & Answers about Прятаться негде, поэтому я не думаю, чтобы он это выдумывал.
Why do we use чтобы here instead of что for "that"?
Because the main clause is negative (я не думаю), expressing doubt or denial. In Russian, when you strongly doubt or deny something, you can use чтобы instead of что to introduce the dependent clause. This triggers the subjunctive mood, adding a flavor of "I highly doubt it's even true that..."
Does выдумывал have to be in the past tense because of чтобы?
Yes! Whenever you use чтобы as a conjunction (whether for purpose, desire, or doubt like in this sentence), the verb in the following clause must always take the past tense form. This is a strict rule for the subjunctive mood in Russian, regardless of when the action actually happens.
Why is it негде, and why isn't there a double negative like нигде не?
Негде is an impersonal negative word meaning "there is nowhere". It is used directly with an infinitive (прятаться) and does not take the negative particle не before the verb. If you used нигде, you would need a grammatical subject and a double negative, such as он нигде не прячется (he is hiding nowhere).
Why use the imperfective выдумывал instead of the perfective выдумал?