I would like to know what is the origin of the expression "all over him/her like a cheap coat/suit". I Googled for it but didn't find any relevant entry. Anyone?
I think it's mainly a BrE expression--a variant is all over him like a rash--commonly used to denote the excessive attention one person gives to another, usually when they've only just met, as a result of a sudden sexual attraction. I suppose it could be used about either sex, but I've only heard it used about a female in pursuit of a male. And the suit metaphor makes it tend that way in any case. Why it should be a "cheap suit" is less obvious, but one characteristic of an expensive suit is that you don't notice you're wearing it. If it's cheap, it's likely to be ill-fitting, made of abrasive material, and continually making its presence felt.
A quick search shows the phrase dates to at least to the 1970s, as quoted in The Miami News (Mar 23, 1974):
Exuding boyish Innocence, he described how, upon arriving at the apartment building, she had invited him for coffee and then "was all over me like a cheap suit."
It's taken from a review of a TV movie called A Case of Rape by NBC, which premiered on February 20, 1974.