STD Grab Bag refers to a person who is so promiscuous that he or she has many STD's (sexually transmitted diseases).
Like a grab bag that you would get at a
birthday as a
child you would pull out many wonderful gifts such as: a pencil, pixie stix, stickers, or a puzzle. But with an STD Grab Bag you can pull out: genital warts, syhpillis, chlamydia, or ghonnorea. Yay!