Inspect A Bridge

To partake in sexual activity underneath a bridge-like structure.

Can be used loosely to suggest sexual activity, with or without the presence of a bridge. Just a disclosed area.

"how about we go and inspect a bridge? ;)"

Person 1: "omg there's someone coming!"
Person 2: "quick. pretend to be inspecting the bridge!"
Person 1: "wow! i really love what they've done with the brick work on this bridge"