>>4840144It's up to the ref's discretion, in cases where it happened in the past he gives the guy a final warning and the guy hops in the ring, there was one match I can't remember with who but the guy on the outside throws the guy coming out into the ringpost and jumps back in so the other guy is counted out.
Refs can also call off the count if one guy is seen to be trying to prevent the other from getting back in the ring.
In NWA and other feds you had to be inside on the other side of the ring or the ref wouldn't count out the other guy.