This is a method of forcibly moving someone, roughly defined as them being carried, face-down, with a person holding each limb. Apparently the London police came up with the phrase “frog’s march,” which is how they handled drunken criminals.
The term has evolved to mean the general forcing of someone to move. Either by literally carrying them, or by pinning their arms behind them and pushing them forward. The term implies some level of intentional humiliation.
The classic scenario would be someone forced to appear in front of a court.