jam, that is, to resist untying after they have been used.
the best way i have found to tie two ropes together is to take the first rope and bring the end around so the rope crosses itself with the end over the length with several inches sticking off to the side. then take the second rope and lay it on top of the first in exactly the same manner. now stick both ends through both loops from the bottom and pull them till the slack is gone. finally pull the other ends of the ropes apart till the knot is tight.
this knot holds the ropes together quite well even when 