Double IP Bonus this weekend

4x IP? The boost stacks with the weekend event. The event is +100% IP, aka 2x IP, and if I'm correct, the IP Boost is +100% as well.
Unless Riot is pulling a Nexon and is making multiplicative items be additive instead...

I loled at the bolded part.

Hm, we'll have to find out and see. If what you said is true (4x IP), well I'm going to be playing quite a bit this weekend, lulz.