#Person1#: Have you decided where to go for the vacation?
#Person2#: I will join John in his mountaineering trip.
#Person1#: Woo cool. Which mountain are you going to conquer?
#Person2#: We haven't made up our minds. Will you come with us?
#Person1#: Of course, I will.
#Person1# and #Person2# will join in John's mountaineering trip.
a vacation