YOU SAID:

guess what i ate yesterday when a clown sat on my face

INTO JAPANESE

ピエロが私の顔の上に座ったとき、私は昨日食べたものを推測

BACK INTO ENGLISH

When the clown sat on my face, I guessed what I ate yesterday

INTO JAPANESE

ピエロが私の顔の上に座ったとき、私は昨日食べたものを推測しました

BACK INTO ENGLISH

When the clown sat on my face, I guessed what I ate yesterday