When you spend hard earn money in making your vagina both sparkle and hurt for the purpose of sex.... and nothing else
Pep1:Did you see D's vagina?
Pep2:No
Pep1: She got it vajazzles, now it matches her phone...
Pep2: Well that sounds like a waste of money.
Pep1: Yeah, and the sex is going to be awkward.
Just as cankles describes a leg with no obvious taper between ankle and calf, and thankles describes the leg with no obvious definition from ankles to thighs, vajankles are the extreme case where there is no obvious distinction from ankle to vagina.