This is not possible passively. You will end up damaging eye or violate chirp sequence or something else. Since USB is kept building on top of old stuff, there are tons of overloads of intelligence over existing stuff.
Hub is one option. But, it is a complex piece of silicon and believe it or not, there are only a handful of silicon vendors that can support hub properly. The TT (transaction translator) inside the hubs is complex and requires tons of tests to make them compatible with all the FS and HS devices in the market.
The other very smart alternative in the market is from a company. (Name escapes me now). They basically NAK to the sender even though they get the data properly, in the mean time forward the data, get the response and when the host retries, they send the proper response since they have received it from the device that they have extended. (Hope this 10K feet explanation gives you the general idea) They had a solid patent on this and were able to build a business out of it.