"To do a bit of stiff" is not a common phrase in English. However, if we break it down phonetically using IPA, we can understand the spelling of each component. "To" is pronounced as /tuː/, "do" as /duː/, "a" as /ə/, "bit" as /bɪt/, "of" as /ɒv/, and "stiff" as /stɪf/. The meaning of the phrase may be unclear but by understanding the IPA phonetic transcription, we can grasp the spelling of each word in it.