Definition from Wiktionary, the free dictionary
- (Singapore, informal) An expression of disbelief, equivalent to Is it so?
2009 December 29, GMAudition, “Audition Story Hack, Letit snow 123bpm for all story numbers 1 ~ 100”:
- u dun understand english sibo?
2010 September 26, Ang Shi Na, “Sheena’s101”:
- Ka ni na, ask stupid question sibo?
2013 August 6, “BlueOldMan, HDB Resales price”:
- You are factoring in the interest sibo?
2015 May 12, May Lee, “Study stress”:
- Grin until mouth crooked sibo?
More common in spoken language than print.