Three middle-aged daddies visit California to have a marvelous time at the beach. When they learn that a nice apartment and an expensive cabriolet isn't enough for them to score with the chicks, they employ a student to help them. At first he's as disgusted of them and his job as his girlfriend, but soon they find out how to use the situation to everyone's benefit.
Looks to be a panhead engine so no later than about 1964.
On the left a Yamaha RD350. Maybe a bigger Yamaha V-twin beside it?
Et la plus grosse, à côté de la 350 qui est tout à gauche, est une... Yamaha XS 650! Youppie...