Are there any current examples of English "Back-Slang"?
Solution 1:
Yob is originally back-slang for boy, as is yennap for penny. In the phrase dab it up with (to sleep with) the dab was originally deb, backslang for bed. Of these, so far as I know, only yob remains in current usage.
For more backslang words, see here... http://people.sc.fsu.edu/~jburkardt/fun/wordplay/back_slang.html
Solution 2:
Polari has the word eek, from ecaf.
How bona to vada your dolly old eek!
Admittedly, that's Julian & Sandy, but I think it also counts as real Polari.