Green’s Dictionary of Slang

sham v.1

[sham n.1 (1)]

[late 17C+] to deceive, to hoax, to fool; to pretend to be or do something.

In phrases

sham on (v.) [1980s+]

1. (US black) to cheat, to deceive.

2. (US campus) to tease, to make fun of someone.