To disappear into thin air / leave without informing anyone of your departure or being seen by anyone, particularly on a night out socialising. Word is derived from the character 'Keyser Soze' from the Usual Suspects, defined by his mysteriousness and ability to disappear without a trace. The trend of pulling a kaizer is viewed with respect by drinking buddies rather than ridicule and indeed people applaud individuals who leave in this manner.
'Where did Collie go last night?'
"I dunno, he pulled a Kaizer around 11. The poor little fella was gee eyed'