You can remember the meaning of 大不了 with this easy mnemonic:
The biggest (大) news of the month is Dalai Lama will come and deliver a speech. The local authorities are concerned whether or not (不) they have the complete (了) crowd-control and terrorist-prevention manpower. At worst, the Dalai Lama might cancel his visit.
Using mnemonics to remember the meaning of Chinese characters like can have an enormous impact on how long to learn Mandarin it takes.