Saint Andrew’s cross is actually a BDSM furniture piece that looks like a cross in a X shape. Basically, the Saint Andrew’s cross is used during BDSM practices to restrain a slave while in a spread-eagled like position. His arms and legs are apart during this BDSM session.
You will often find this BDSM furniture piece in a BDSM dungeon. Arms, wrists, ankles and sometimes even waist are being tied, the slave facing the front or the back. If the slave is faced front, he can be teased easily as he can see what is going on, while spanking, flogging or whipping.