Portmanteau of the now not often heard 'twee' (describing something excessively quaint or cutesy) and 'weird'. Thus meaning something so twee as to become uncomfortable or weird.
Man: I've heard that Susan in accounts is obsessed with Sylvanian Families and spends all evening making clothes for them and talking to them and stuff.
Woman: Aaah what? Man that's tweeird!
Woman: Aaah what? Man that's tweeird!
by RemainsAnomynous October 28, 2009