hop on, v. — Green’s Dictionary of Slang

hop on v.

1. to have sexual intercourse.

1918		in E. Cray Erotic Muse (1992) 311: Columbo had a one-eyed mate. / He loved him like a brother, / And every night at seven bells, / They hopped upon each other!
1966		Trimble 5000 Adult Sex Words and Phrases.
1999		L. Gould Shagadelically Speaking 61: hop on the good foot and do the bad thing, A sexual encouter.
2021		L. McInerney Rules of Revelation 145: ‘Hopping on and off each other is how those two say hello’.

2. to put pressure on.

1931

D. Runyon ‘Romance in the Roaring Forties’ in Runyon on Broadway (1954) 35: The newspapers hop on the cops and the cops hop on everybody.

3. to attack, to beat up.

1928		M.C. Sharpe Chicago May (1929) 64: I was mad, hopped on him, told him he had a nerve to steal from my friends, after the way I had befriended him, and ordered him to return the cover (overcoat).
1998		K. Sampson Awaydays 96: Even if they support Liverpool or Everton they’re getting hopped on [...] after the match.

4. (US teen) to take an admiring look.

1949–51

in M. Daly Profile of Youth 232: ‘Hop on that!’ says a York, Pennsylvania, high-school boy when he sees a pretty ‘skob’.

In phrases

hop on a babe (v.) [babe n. (3)]

(US campus) to have sexual intercourse; the implication is that the man, lacking greater finesse, has made a pounce (prob. when drunk) to initiate the activity .

2002

‘MommaKin’ EliteFitness.com Forum 25 Jan. 🌐 hop on a babe.