It's not really a joke but you can confuse someone on April fools day by saying that it's not April fools day and then say that it is opposite day and keep confuse them by saying that your kidding about opposite day but then you say that because it's opposite day you really mean that it's opposite day when you say it's not.
It's not really a joke but you can confuse someone on April fools day by saying that it's not April fools day and then say that it is opposite day and keep confuse them by saying that your kidding about opposite day but then you say that because it's opposite day you really mean that it's opposite day when you say it's not.