转贴某人解法（一点启发）

Take out 3 cakes, ask 4 baby eat one of each, in total 3 groups.

2 groups must use same time, say it's A minutes.
1 group which has Shuaibaby must use a different time, say it's B minutes.

Then, take two baby from the last group, feed them the 4th cake.

If they didn't use 2A minutes to finish, then Shuaibaby is one of them. Feed the fifth cake to anyone of them see whether they can finish in 4A minutes. Then you know he is Shuaibaby or not.

If they did use 2A minutes to finish, then Shuaibaby is in the other two. Feed the fifth cake to one of the other two.

（评：如果你有表的话当然就容易些，如果你有称的话就更简单了，但如果没有这些东西呢！）