It is colloquially said of a 'wedge' , a 'small piece that fits into another and serves to hold or fix a third' . They have the same figurative meaning as "contact (social, labor), influence or irregular help to participate in a situation without the necessary merits or resources". By extension, any small mechanical part of which the technical name is unknown. Surely the name comes from a derogatory pito . See pendorcho, pirulo, lever (figuratively).
