I wanted to mention that ‘lad’ has certainly been subject to pejorisation — just not in the USA. In Australia it is used to refer to an underclass subculture (often associated with petty crime) that is similar to the term ‘chav’ in the UK (although the latter is gender neutral). In the UK the term ‘lad’ and ‘laddish’ grew in usage in the 1990s and referred to young, educated men who indulge in emotional incompetence, sexism, violence, anti-intellectualism and drunkenness (the TV show ‘Men Behaving Badly’ could be a good reference point for this).
Please forgive the profanities that follow, but I wanted to add some words used with a rather negative intention that have been left out which were very common in my teen years in Britain (where and when the full form of Pussy Cat was used to describe a weak-willed man or a less-scary-than-you-would-initially-think woman — much more than the association of the word ‘pussy’ to female genitalia which I feel is quite a North American phenomenon):
mat finish (a circumcised penis)
scrot (short for scrotum)
dick and dickhead
any allusion to sperm where one can get quite creative.
any allusion to masterbation which was thought of as an almost exclusively male activity in our adolescent naivety.
anything referring to male homosexuality.