Because languages [and the people who use them] are very creative it
is probable that the Kenyan man was using 'mitumba' or 'mivumba' as a
sexist slang, an equivalent to 'used' or 'off-layer', terms used
elsewhere to describe women who ahve aged either because of child
birth or by abusing their bodies.
To give you an example from my experience: I was translating a play
from Luganda (one of the 34 languages of Uganda) into English. In the
play one man describes a woman who you may compare with the 'shebeen'
ladies of South Africa, she runs a bar in her house, is aged and has
changed men several times, and has a grown up daughter, as
'oluziina'. The literal meaning of this is a worn out shredded and
sometimes dirty piece of clothing. The nearest I could get to the
original meaning of the word in the play was: 'the shreds of a
woman'....
Does this make sense?