Heck, even a ball python. Mine has done that to me a couple times and even with his size his strength is deceptive. Granted I probably could easily pry my hands free and it's more of a matter of carefully encouraging him to move off so I don't hurt him, but the point is any snake that relies on constriction (and even those that don't) shouldn't be underestimated regardless of size. That tube of a body is all MUSCLE, and they know how to use it.
On a different unrelated note, even the danger factor aside, I genuinely don't believe most people have the facilities and resources to house a full sized retic. These are massive animals that nonetheless deserve the same amount of space and enrichment that any other snake does, and unfortunately their equivalence would be akin to that of half a single bedroom apartment to be adequate. The number of retics and burms I see shoved into prisons so small they can do little but coil and sit in a corner is embarrassing (the 4x2 my yearling corn snake is in used to house the previous owner's burm for example and the pic I saw had it taking up half the space just from being coiled into a mound).