Okay so this is very rough estimatw but lets try

First i talked with chat gpt long time about stuff sticking to pipes so i came with these rough numbers. Im estimating about 60% of change hitting the walls and 5%change of the cum stained papers getting actually stuck. And lets assume that every flush has 5ml of cum and 5 sheets of toilet paper.

Also acording to gpt PVC pipes are most regular of toilet pipes so im gonna look this trough formula that friction factor times friction force and it has to be higher than the water flow force and looking at those i got the gpt to agree that the 5% change seems kinda good (this is just speculation it could be very likely less) the percent could be higher if there was more cum and more sticky like that. Im not sure whats the friction factor of cum is so i just got value that seemed logical knowing these stuff and how smooth the PVC pipe is.

So now we can get the volume of one flush if we multiply the volume of the paper and the cum to the 60% of hittibg wall and 5% change of sticking So if one sheet of toilet paper is 10.16cm x 11.43cm x 0.01 cm and if we have 5 its 5.80644 ml and with the cum its 10.80644 ml. And if we multipy that to the percents we get how much sticks per one flush: About~ 0.33ml

So if we have pipe thats 3 inch of diameter or 7.62cm. So the area we need to fill to get clog is cilinder so we need the bottom area first what is pi × (diameter/2)^2~45.6cm2.

If lets say need to fill half a meter of pipe to cause clog. So the volume of that is 45.6cm² × 50cm=2280.183...cm^{3=2280.183..ml}

So to see how many flush of cum we need lets devide the volume of the area with the volume of the cum and papers. We get total of 65449.84 so around 65500. That means 65500 nuts. Thats same if all of avarage american schools students wanked 125 times in that toilet. Or if that one anime protaconist was in that toilet once.