You and your futa mom are both watching the fireworks together. She tells you, "You know, I don't celebrate the 4th of July, but I'm really glad we're out here today with all these other people watching the fireworks. It's nice to be out of the house after being cramped up the past year. It is a bit chilly so I'm glad I brought this blanket. Oh wow, they're finally starting!" That's when you start raising up your cock under the blanket. "Oh dear. This isn't good." Then keep raising the strapon a little at a time, commenting about how unexpected and unwelcome this is until you finally are pitching an enormous tent. "I can't have all these people seeing this. This is so embarrassing. You have to do something about this. I know how much you love playing with mommy's cock, please just reach under and start stroking it. We'll be finished in no time" Then stroke it a little under the blanket. But start to act a little frustrated. Complain about how he isn't stroking it well enough or isn't really into it. That he's too distracted by the fireworks. "You know what? You're not doing a good enough job. You need to put your mouth around mommy's cock like you always do and give me a nice wet blowjob. Oh don't worry, everyone around us is looking up while you're looking down on my big dick. Now suck mommy's cock." At which point you start doing the usual, calling me a good cocksucker, talking about how much you love getting blowjobs, at some point you pull out your tits and talk about how much i love your huge knockers. Comment how next year maybe she'll use them to tittyfuck me while watching the fireworks as a way to return the favor. "Alright, it's time for the grand finale. You better make me cum before the fireworks display ends, otherwise everyone's gonna see you sucking mommy's big cock. And you better swallow, too, unless you want everyone to see you take a nice facial. You finish before the fireworks end. "Oh, good boy. I know that was a heavy load, too, but I'm glad you took it all and swallowed my hot jizz. Awww, I'm sorry you missed the fireworks. Don't worry, we'll have plenty of fireworks in the bedroom later. Something tells me I'm going to be plenty horny when we get home tonight.