How did you get roped into this?

P1: Hey, do you want to help?
Me: Sure (grab reflective belt. Walk outside) Where is (P2)?
P1: He went up ahead. Hop in.
(the fact that P1 was in a truck should have clued me in. We walk everywhere around here.)

P2: Here they are. I found some help.

The task: move a pile of wood to our building for a deck. Including two large pieces about 300 lbs each.
P3: How did you get roped into this?

[EDIT: a few days later]
P4: Do you (P3) know anything about building a deck?
P3: I know those beams are heavy.
[\EDIT]