Green’s Dictionary of Slang

bumbo-claat n.

also bombo-claat, bumbaclot, bumbo-clot, bumbo-cloth
[bumbo n.2 (2) + SE cloth]
[1950s+] (W.I.)

1. a sanitary towel.

2. a highly derog. term of abuse; also as an excl.

3. attrib. use of sense 2.

4. a euph. for fuck n. in various senses.