A connector and a method of anchoring the connector to a first object that includes providing the connector having a sleeve element and a piston element with a shaft portion, providing a through hole in the first object, and inserting the connector through the through hole and until a distal portion of one of the sleeve and/or the piston element rests against the second object. Mechanical oscillations are coupled into the piston element while the piston element is pressed towards the distal side, and thereby liquefying portions a thermoplastic material at an interface portion between the sleeve element and the piston element while a periphery of the interface portion is adjacent the circumferential wall, and causing the liquefied thermoplastic material to flow radially outward from the periphery and into structures of the first object and/or along an inner surface.