When a member of the home team scores a hat trick, it is normal for fans to throw their hats on the ice (usually causing a delay). Does the same apply for when a member of the away team scores a hat trick? Is it 'frowned' upon to throw your hat on the ice if you are cheering for the away team ?
It depends on circumstances.
The general rule is a fan will not throw a hat should a player from the opposing team score a hat trick. So, for the most part, nothing will happen.
However, depending on how many away fans are at the arena, you may see some of them throw hats on the ice.
Normally the hats are scraped off and donated.
In the NHL nowadays, there will be fans of the away team present in the arena. Therefore it is possible that hats will be thrown onto the ice if someone from the away team scores a goal.
The hats are usually scraped away and donated to charity. But this does not happen very often since hat tricks are not scored every day.