About almost 1/2way through the game, when you're in 1st person mode in the apartment and investigate the toilet, you're told that something is inside and then asked if you'd like to grab it. Sadly, if you choose "yes", Henry admits to himself that he isn't brave enough to reach inside (unlike James from SH2) and fans are left with the lingering question...
"What was inside Henry's toilet??"
So here's a chance for everyone to ponder and imagine what would've been inside good ol' Mr. Townshend's toilet!
I think it was the set of keys to get out of the apartment (Keys of Liberation), but Walter knew Henry was a bit of a coward and wouldn't do it so it was like a sick joke. After Henry forgets about what was inside the toilet, Walter puts it inside his corpse's coat pocket so Henry would have to suffer a bit more in order to get it :D