You can visit people's profiles and click on the link that has an item with "Trick or Treat!" under it.
If you're on the forums, a lot of people will have the ToT link in their signature that you can easily click on (like the one in my own sig). You can put the link in your signature here (click) by using this code...
[tot=Lirrie]
You can also use the random trick or treat link for shorter wait times and smaller chances of being hexed.
https://subeta.net/profile.php?act=trickortreat&random=true
@ Lirrie There are many ways:
[tot=USERNAME]On the Morostide forum there are many threads for this (contests, ToT the user above etc) and guides.
[Edit] Ninja'd :( don't post in your cellphones kids
I don't know if anyone else has this problem, but clicking an already generated link to the random trick or treating results in a lot of site-hang for me. I go to the News page and click it new each time from the icon there on the RH side of that page