Holy Cats! you don't
know the magical choco-love / liquid

ss-kicker

that
is an 'ICB'??
OK, So, get 1 nicely chilled pint glass, preferably with 'smooth sides'
(for easier gulping 
, filled, ~ 1/2 - 5/8's with
(preferably) cold, but not *too* cold, nice frothy Guinness... draught in glass, is-best, but the 'tall cans' will do, in a pinch...
Then, in
(preferably) a 1 1/2-shot shot-glass, fill with 1/2 Baileys,
(preferably first..) and 1/2 - yep - Jamesons, let 'settle'...
Then, prepare your favorite 'arm-chair' / rocker / sofa / bed, etc
(...cause those are nicer than the floor, mind you... 
take the pint of Guinny in one hand, and the shot-glass in the other, and... *ka-ploonk*, drop 'er into the pint! At this point, it will quickly 'curdle', and begin to look like cat-yack

but don't worry, you'll be fine...
Now, *most importantly*, drink it down to the bottom,
in one fell-swoop.
(...but take care not to chip a tooth with the shot-glass.. 
Important to get the proper 'progression', from 'bitter Guinny-start', moving on into the warming Jameson-rush, then, the all-important, Baileys-mixed-with Guinny lip-smacking 'choco-love finish'... Buuuuuurp!
Repeat.
(...but not more than 3-4x, or...well, remember what I said about 'cat yack'?
(Disclaimer: Not-responsible for 'trading one vice for another' - if you kick the rollies, only to get hooked on 'ICBs', you didn't get this recipe from me, we didn't have this conversation, I don't know you...
njoy...

cheers.
j