Mirc
Not mIRC!!!
It's called [wiki]L-vocalization[/wiki]. Basically, in some English dialects, most famously Cockney (although it has been spreading) - [l] in coda position (as this become /w/. So milk becomes /miwk/.
So I won't sound weird if I'm pronouncing it in "vulnerable", right? That's all I need to know!

(actually I'm quite fascinated by the differences in various English accents. It's just that I've never heard of this one before, so I suddenly worried about the way I am pronouncing those words. It's good for me to know it's not very widespread, so I won't have to change it in order to sound more like a native)
Actually the same change happened in Romanian, with most of the Latin intervocalic Ls becoming weaker and weaker over time. But because of the fact that we don't really like approximated, weak sounds, it completely disappeared as time went by, so there's no "weak L" sound like in Polish. In my language, those Ls either went weaker and weaker and finally disappeared, or they were made stronger through Rhotacism, and became Rs.
Sometimes BOTH changes happened to a word, rendering two different variants of the same original Latin word, like it happened to the Latin verb "volere" (=to want), which became "vrere" and "voire" (out of use in modern Romanian, though still present in words like "vointa" = will).