Yaya :show off; behave in a self-important manner, arrogant, boastful, proud, stuck-up.
1978 Leong Choon Cheong《 Youth in the Army 》: yaya means showing off, to act as though one is very important. ‘Don’t yaya around’, ‘Don’t talk yaya’, ‘Got nothing want to yaya’ are common sentences with the slang ‘yaya’ incorporated.
1985 Michael Chiang 《Army Daze》 Yaya -Nonchalant; also one who acts tough. E.g., ‘Who gave you permission to smoke? You don’t simply yaya around here, understand?!’
2003 Teo Pau Lin (quoting Anthony Tan) The Sunday Times (LifeStyle), 19 October, He thinks he got money, very ya-ya. I don’t like to talk to him.