If you don't want to make friends, you can express your ideas in a humorous way. For example:

1. "I am a lonely loner, and all my friends have left me because I am so unique."

2. "I am cultivating immortality, and I can't have friends to interfere with me."

3. "I think my circle of friends is big enough now, and adding new friends may cause global warming."

4. "My friendship warehouse is full, and I can't hold any more friendship."

5. "I have evolved into a creature that only makes friends with computers."

These are humorous and polite replies, which can help you express your ideas euphemistically.