Realizing that as things were now, the truth was eventually coming out anyway, Biff pressed. How hard could it be to prove something as obvious as him not being Jon, anyway?
"You know what? Fine, don't believe me, but there's a much more real, tangible issue that will keep me from leaving the house until it's resolved, and it can't be explained otherwise!"
"Mom!" Sarah called out. "Mom, Jon's being weird!"
"It's the clothes, Sarah! Besides the one or two sleepware bits I'm wearing right now, all of it's too small! And not just a little too small, 2 or 3 sizes too small!"
By now, Sarah had her back turned and was walking off to find their "mother." "Mom!" Sarah called when she found her, in the kitchen, a pot of coffee on the brew.
Biff followed Sarah and continued just as though nothing was happening. "You can't explain why I'd own clothes as small as that! My wardrobe was meant for someone else, someone smaller, and someone definitely not here!"
Linda looked tired and irritated by the disturbance, but she mustered her patience enough to ask Sarah "What is it, honey?"
Biff continued "You can check my wardrobe if you'd like, and see for yourself-"
"Jon, hush!" Linda hissed at Biff, silencing him for the moment. "Sarah?"
"Jon's been acting all weird this morning. He says he's not Jon and that he's someone else, and he's kinda scaring me," Sarah replied.
Linda turned expectantly to Biff. "Well, Jon, do you have anything to say for yourself?" She asked in that warning motherly tone.
"It's true. I'm not supposed to be here, and I think I can prove it. In fact, I kinda have to, I can't leave the house until the wardrobe issue is sorted out."
Linda was not amused. Apparently she had expected an apology, not a doubling down. "Don't be absurd, son, you've lived here with us for years. Now, apologize to your sister and get dressed."
"I can only do one of those things," Biff replied. "I'm sorry if it's scaring you or I'm coming off wrong about it or anything, but the fact is that my clothes are not mine, and neither are any of the rest of Jon's things."
"You're being ridiculous, Jon!" Sarah complained. "What kind of magical snap would have to have happened for that to even be possible?"
"Am I not bigger than the old Jon? I can show you to my room right now!" Biff retorted.
"Watch your tone, both of you," Linda warned as the pot of coffee finished. "We don't have time for this, children. School will be starting soon, and this bickering is going to make you late at this rate. Is Mikey up yet?"
"Here I am, mommy!" Mikey had entered the kitchen and slipped a poptart in the toaster unnoticed, and was now watching the commotion with interest.
"Good, good, at least he's ready. You other two still need to get dressed for school. If there really is some issue Jon has with his clothes, I'll come take a look at it, but we have to hurry."
"Right, right," Sarah said before scurrying off to her own routine. Biff had no choice but to go along with it, for now. Arguing for any better seemed hopeless.