be (just) along for the ride

To be attending some event or participating in some activity without playing an active or central role in the proceedings. John's receiving an award for his work overseas tonight, and I'm just along for the ride. I'm going along for the ride to my friends' book club meeting later to see if I want to become a member. Oh, I have no interest in playing basketball with you guys, I'm just along for the ride. Consider me your cheerleader!