1. angry [adjective/adverb]
When declining "boos", the "s" changes into a "z": "boze". See the examples.
Examples:
- "Waarom kijk je zo boos?"
("Why are you looking so angry?")
- "Frank was vandaag in een boze bui, omdat iemand zijn auto bekrast had."
("Frank was in an angry mood today, because someone scratched his car.")
- "Ik ben een beetje boos, want hij is alweer niet op komen dagen!"
("I’m a bit angry, because once again he did not show up!")
Expression:
- "Ben je boos, pluk een roos! Zet ‘m op je hoed, dan ben je morgen weer zoet!": literally this means "Are you angry, pick a rose! Put it on your hat, then you will be sweet/good tomorrow". It is actually more of a children’s rhyme and parents say it to their sulky children. Adults often use it too, but usually only the first half, since everyone assumes you know the rest 
2. evil [adjective/adverb]
Examples:
- "Boze tongen beweren dat de CEO geld witwaste."
("Evil tongues claim that the CEO laundered money."
- "De boze fee veranderde de kinderen in kleine padden met één slag van haar toverstok."
("The evil fairy changed the kids into toads with one stroke of her magic wand.")
- "De boze plannen van de schurk werden verijdeld door 007."
("The villain’s evil plans were frustrated by 007.")
Expressions:
- "Dat is uit den boze!": That’s absolutely not going to happen! Lit.: That is from the evil/godless.
Related words:
- "Kwaad": angry, evil. Synonymous to "boos".
- "Kwaadaardig": malicious.
- "Nijdig": cross, angry.