Without hesitation

You can't explain why, but the thought of shoving your cock into Allison alongside your mother's sends a jolt of excitement through you, and without stopping to consider any further, you get into position behind your girlfriend.

Your cock throbs as you push your hips forwards, quickly slipping into the condom that covers your mother's enormous cock...thankfully, with the massive size of Helen's dick, stretching the condom out a bit to accommodate you doesn't seem to be too much of a strain.

You need to push harder than expected to finish entering though; your girlfriend's pussy is quite full, and only your comparatively tiny size let's you slide your way in.

The first thing you notice aside from the tightness is the heat - being so snugly pressed against your mother's cock makes you feel how hot her member is...you think you can even feel her heartbeat as her massive dong throbs against yours.

Though you're inside Allison, her pussy is separated from you by a condom, so you're actually far more conscious of Helen's cock as you try to adjust to the novel sensation of having so much...pressure on your dick.

"Ooooh, I can feel your cute little cock trembling sweetie..." she gives Allison's rear a perfunctory smack. "Tighten up dear, I'm enjoying some bonding time with my son." Allison seems lost in a daze, but agreeably squeezes her pussy tight around the two of you, letting out a moan as she does.

You can feel your cock being pressed against Helen's all the more tightly, and let out a strangled groan as you try not to cum before she even starts moving.