wallah

From Arabic (والله), an oath formula meaning 'by God' or 'I swear'; often explained as a short form of 'wahayat Allah' ('by the living God'). Spelled with 'w' the form is Arabic, with 'v' (vallah) typically Turkish. Young people with Arabic and Turkish roots brought the exclamation into German youth slang, where 'Wallah!' serves as a tag to reinforce a statement ('… really, wallah!').