Possible justification(s) for... toys?

I think my fear of the wife's ire has just been surpassed (finally) by my need to possess Lego Mindstorms. A new Mindstorm-ready version of the LabView Toolkit is coming. Cool! My oldest kids are soon to be 7 and 8 years old, that's old enough, right? I'm pretty sure the Home Boss won't concur. If you were going to buy some Mindstorms and wanted to avoid sleeping on the sofa, what would your justification be?

By the way, there's a rumor that you could be arrested for goofing off with your Legos in Europe. Play carefully!