View Your Friends' Trips
As of Tripsy 3.5, you can be added to a trip even if you're not travelling with the organiser, this is great for sharing trip plans with friends or family without them getting unwanted notifications etc.
To see trips where you've been added as not travelling with the organiser, tap on the 'My Trips' heading from your trips list, you'll then see the 'Friends' Trips' option. To change back to viewing your own trips, tap the same header and you'll be able to switch back and forth.