what to do with the sperm

"Extra"? Do you mean after masterbation? If so, just get some tissue or paper towels and clean up the mess then flush down the toilet. Just don't use too much and stop up the toilet. If you throw it in the trash, the smell may give you away to your parents which might lead to some awkward conversations or explanations.

Semen will stain carpets and blankets. It will leave stains on white as well so be careful where you aim.

i find that white socks are good, but im one of those people who wears ONLY white socks, and you might not have loads of them. im 16 and my mum probably expects me to be masturbating, but she doesnt check the inside out socks when she does the washing :-) and its perfectly clean, socks get worn, socks come off, socks get used to clean, socks get washed... the cycle continues.

You might be surprised to learn how much she DOES know. Women, especially mothers, have a strong nose for semen and she certainly knows why your socks seem extra crusty and sticky but she washes them to avoid having to discuss it. Out of respect for her, either do your own washing or find another method for disposing of the jizz.