Whoever says, ‘give’; it is as if he said ‘acquire it’ - כל האומר תנו כאומר זכו דמי
Summary:
תן כזכי is effective only when there is a דעת אחרת and only when the item is transferred at the time תן is said. מעמד שלשתן is effective even if the item is not in the possession of the נפקד and even if the נפקד is unwilling to be זוכה.
[Alternately], (in addition) תן (והולך) כזכי applies only to a מלוה (or שחרור עבד which is similar to a מלוה), but not by מתנה