detroit double-reacharound
The Detroit Double-Reacharound is when you wrap your arm around your victim and hold them in place, then slowly but snugly slide your entire fist inside their anus and hold them like that.
And just as she climbed onto the bus headed home, the man behind her slid his arm under hers and gave her the ol' Detroit Double-Reacharound. Becky's ride home just got a lot comfier.