You might remember the meaning of the character 不 with this easy mnemonic:
Your friends dared to you rattle a <strong>wasp</strong>'s (不) nest. You did it because you were not very bright. "<strong>No</strong>!" you screamed and ran away as an angry swarm of wasps started to chase you.
Using mnemonics to remember the meaning of Chinese characters like has a huge impact on how long to learn Mandarin it takes.