Suckling Disease
a rare form of metaphorical sexually transmitted infection that is aroused when more often a woman has been performing the act of "suckling" on a day to day basis to strangers and therefore has acquired the disease due to repetition of the disgraceful act.
when you visit your best mates house and find that his mother is more than willing to have a nosh even though not much interaction is needed because she has previously acquired the highly rare "suckling disease" meaning she will have a nosh in any circumstances with any stranger, no cash in hand needed due to the disease being present.