First dig a staircase down to bedrock. These is also a great way to find caves with diamonds. Anyway, when you hit bedrock go 4 blocks up your staircase. Then make a room 3 blocks heigh and really big. Now light it up really good. You could use torches, Jack-o-lanterns, or glow stone. I don't now if you can do it on peaceful. Check it every IN-GAME morning to see if any are there
Chat with our AI personalities
You can find slimes in flat areas at lease 6-7 blocks wide. Or in slime dungeons.
there are magma cubes but no slimes.
In the bottom layers of the map or (if you have Weekly Snapshot 12w40a or above) in swamps.
step 1 find slimes underground (hint: look DEEP underground) Step 2 make the area where you found slimes easly accseable step 3 kill all the slimes step 4 leave and then later come back to kill more slimes step 5 ?????? step 6 profit
Yes, Slimes are hostile and will attack players on difficulties other than Peaceful (they won't appear at all in that), or Creative Mode.