Similar to spidermanning and supermanning it derives from a popular comic book character. "Aquamanning that ho" consists of fucking a ho from behind in a bathroom setting. To be more specific directly over the toilet bowl with a functioning flush mechanism. Immediately before ejaculation you slam that ho's head into the toilet water and proceed to flush during the skeeting process. This phrase is originated and copywrited by E. Right outta the ROC.
Aquamanning that ho can only be conducted on some down ass bitches or the dirtiest of dirt. (see aquaman that ho definition above.)