The standard RV plug is typically a NEMA TT series as shown below.
 NEMA TT–30
NEMA TT–30 plug and receptacle. (The center hole on the receptacle is not a contact.)
NEMA TT–30 is a 30 A, 125 V recreational vehicle standard which may also be known as RV 30. It is frequently (and sometimes disastrously) confused for a NEMA 10–30. The RV receptacle is common in nearly all RV parks in the United States and Canada, and all but the largest RVs manufactured since the 1970s use this plug. The hot and neutral blades are angled at 45° from vertical and 90 degrees to each other, similar to NEMA 10 devices. The plug is slightly smaller than a NEMA 10 but larger than ordinary 5–15 plugs. The ground pin, however, is round, like those on straight-blade NEMA grounding devices. Referring to the diagram, the orientation is the same as the NEMA 5 plug and socket, with the receptacle neutral on the lower right. Due to the appearance of this plug, many people assume that it is to be wired for 240 V, but this is a 120 V device. Adapters exist with the TT–30 plug on one side and a 5–15 or 5–20 socket on the other side. When the cord is detachable from the RV an L5–30 is usually used on the RV end of the cord.
Or are you referring to something like this lockset connection from Marinco that is becoming more common.