I was on UAL 129 traveling IAD-ORD and we were #2 for runway 27L to ORD on Friday night. Before us there was this AA Md-80 and another United was just landing on the runway. ATC told the UAL 327 to get out of the next high speed taxiway and expedite the exit. for some reason the UAL 327 couldn't make it on time .. ORD TWR: United 327 I told you to expedite.. break .. American XXXX go around fly runway heading .. Contact departure. AA XXXX: American XXXXX going around. (I wish I was in that machine, never did a go around in a commercial airliner) TWR : United 327 , what are you doing parking on the runway? .. break .. United 129 cleared to land. After a bit of silence UAL 327 decided to come back. UAL327: We didn't park on the runway TWR: I don't think you want to go there and I don't think you want to park on the taxiway all night long.. It was interesting to say the least.. BAHA Fan of Ch.9