CT3WA-E44MV-FXFWF?
? = First letter dangerous African animal; You know it better as a "Hungry Hungry _ippo" (H)

MLLTN-YYN97-V8V4?
? = First letter of the spelled out version of the number 0 (Z)

CHDOQ-XYH2N-42RB?
? = First letter of Australian animal that only eats Eucalyptus leaves and hangs out in trees (K)

DG533-NTF3K-EHEZ?
? = Integer that rhymes with sign (9)

k2A76-3B78N-CJ?B8
? = Pronoun used to refer to yourself in first-person (I)