If I have 5 bottles in one hand and 6 in the other hand, what do I have?
Math Teacher: "If I have 5 bottles in one hand and 6 in the other hand, what do I have?"
Student: "A drinking problem."
This is a joke that is based on a (presumably) intentional misunderstanding of a question. The teacher meant "how many bottles do I have", when he or she said "what do I have?" The student took it to mean "what ailment do I have?"
Both parsing of the sentence are possible, however the first one is the obvious one, and for someone to be talking to their math teacher and not expect that they are being asked a math question is sort of weird.
Finally, I wonder how the student imagined the teacher carrying eleven bottles of alcohol at the same time, as that would be really difficult assuming normal bottle sizes.