In his 1990 classic "U Can't Touch This," MC Hammer told his millions of listeners to "Stop - Hammer Time." And while that makes no sense it reminded me of riding the bus.
Because when you get to your stop and it's time to transfer things can get a little, well, funky - especially if you're not sure about the rules. Luckily the rules are pretty straightforward and TriMet has a webpage describing them.
Here's the quick version: Look at the time printed at the top of your MAX ticket or bus receipt - that's how long your fare is valid for. Generally, you get two hours to transfer which should be plenty of time unless you have a Doctor Jeff-like commute. Make sure you keep your bus receipt or validated MAX ticket to show when you board your next bus or train.
That covers most transfers, but if you are going between C-Tran and TriMet it gets a little tricky (funky?). The image below is from TriMet's website. It lays out how fares work between the two transit agencies.