Have a Triangle Foot Tickle

This is how three "friends" can become closer to each other through holding a "triangle" foot tickling.

Steps

First get three friends together.
Find some place that has thick carpet and is somewhat sound proofed or isolated.
Then each of you sits with your legs overlapping a leg of each other, forming the edges of a triangle. The legs should overlap in the picture.
Then tie each pair of legs together (ankle to thigh) with 6 pieces of soft rope or a few scarves forming a triangle.
Now, since each person has one of their friends feet on one side of their thigh and one of their other friends feet on the other side of their thigh, each one of the friends uses their fingertips on each arch before them.
If two friends gang up on the third person, this can lead to an incredible display of hysterics.
The tickling delight can alternate. Two friends can tickle the third to a count of five. But be careful of friends who count to four and then tease you, saying, "Four and a quarter, four and a half, four and three quarters..." This can lead to an incredible display of begging and pleading, if they are not already out of breath from laughing their heads off.

Make sure that their feet are as ticklish as your feet.
Have room behind your backs for falling backward on to the carpet; or have soft comfy chairs behind each person so that each of you sits upright.
Since begging and pleading for the tickling to stop is part of the fun always use safe words: e.g. "red" for stop and "yellow" for pause.
Since asking to be tickled takes most/all the fun out of it have some signal: e.g. wearing clothes with big buttons, wearing green socks.
If your friends don't want to do it then don't try to force them. As they may not be comfortable doing it!

If some unexpected guests arrive, then rib cages (and underarms) might be tickled.
These extra guest(s), may feel the need to tickle each of your rib cages in turn, since you are fairly immobile, with your legs tied together. This could lead to uncontrollably hysterical laughter.
If the room is not sound proofed or isolated, your laughter may attract the attention of others.
Make sure that there are only the three of you.