OK... coz you wants a leeeetle fun, riiiiiight? Don't travel at rush hour if you can avoid it... but DO travel by train.... here goes
DO sit down
DO make sure legs stick out
Watch all the people strying to be considerate as they "cross-country" across you to avoid touching your legs... how far will they contort and put themselves out to avoid giving you any discomfort...
Watch all the faces as people glance at your injury and try to figure out what you have done...
When people do ask you, be a different persona each day... and try and find as many different ways to tell your story as possible... you know... give an "organ recital" where you go into medical detail like a docomentary, another day give a version of someone who can't stand pain but has to go in to every detail anyway, then a version of someone who regularly breaks their body in daring death-defying feats and this is as no more than a scratch...
Could be a lot of fun!