how to get if stamens to check for multiple values in array

Im having some trouble with this

$AuthUserIDs = array('299816740352593','1783393008638862');

foreach($AuthUserIDs as $AuthUserID){
  if($userID == $AuthUserID){
   //DO SOMETHING
   }
}

I can't seem to figure out what to say in the if statement to check for the multiple id's from the array?