road to nowhere: is there anything in the Bible on wanking?
Nope. The WTS used to refer to Colossians 3:5. The NWT translates it as follows:
"Deaden, therefore, your body members that are on the earth as respects sexual immorality, uncleanness, uncontrolled sexual passion, hurtful desire, and greediness, which is idolatry."
The New International Version translates it this way:
"Put to death, therefore, whatever belongs to your earthly nature: sexual immorality, impurity, lust, evil desires and greed, which is idolatry."
Even if we allow the NWT wording, it's tough to say that this explicitly condemns masturbation. The Bible seems to be silent on the issue otherwise; trying to interpret Onan's crime --disobeying an order from God-- as a condemnation of masturbation is a stretch, to say the least.