Green’s Dictionary of Slang

dry fuck n.

[SE dry + fuck n. (1a)]
(orig. US)

1. [1930s+] (also dry rub) a simulated act of sexual intercourse, without penetration and usu. without removing the clothes.

2. [1940s] in fig. use, something tedious or disappointing.

3. [1950s+] (gay) anal intercourse without any form of lubricant.