Obama asked Biden to swear in senior members of the White House staff during a press conference Wednesday.
Biden may have had a senior moment instead, forgetting momentarily what he was supposed to do.
Obama: Joe, you want to administer the oath?
Biden: Am I doing this again? Oh! For the senior staff. My memory's not as good as Justice Roberts' ... Chief Justice Roberts.
Obama, not looking amused, gave Biden a tap on his back with his right hand in an attempt to get his VP back on track.
The oath then took place without any more incidents, but Biden did get some laughs from staffers and the press corps.